- Configure boot partition
Expose the interfaces that used to enable the configurations
of the boot mode of the eMMC cards.
usage how-to and examples:
Enable the boot partition 1 boot enabled.
"echo 8 > /sys/devices/soc0/soc.1/2100000.aips-bus/
219c000.usdhc/mmc_host/mmc2/mmc2\:0001/boot_config"

In order to make sure that the re-read the ext-csd of card
can be completed successfully, add the method to wait for
the finish of the busy state.

- setup boot_info message output
Output bit means of important esd_csd register

Read esd_csd info each time when cat boot_info
becasue user may change config affect esd_csd
value.

- Boot partition access howto:
About the details, please refer to the guidance of
Documentation/mmc/mmc-dev-parts.txt

To enable write access to /dev/mmcblkXbootY, disable the forced
read-only access with:
echo 0 > /sys/block/mmcblkXbootY/force_ro

To re-enable read-only access:
echo 1 > /sys/block/mmcblkXbootY/force_ro

NOTE:
- The definitions of the EXT_CSD_PART_CONFIG and EXT_CSD_BOOT_BUS_WIDTH
+------------------------------------------------------------+
| Bit7 | Bit6     | Bit5 Bit4 Bit3        | Bit2 Bit1 Bit0   |
|------|----------|-----------------------|------------------|
| X    | BOOT_ACK | BOOT_PARTITION_ENABLE | PARTITION_ACCESS |
+------------------------------------------------------------+
Bit7: Reserved
Bit6: always set to vaule '1' when boot_part is enabled
Bit[5:3]:
0x0 : Device not boot enabled (default)
0x1 : Boot partition 1 enabled for boot
0x2 : Boot partition 2 enabled for boot
0x7 : User area enabled for boot
Bit[2:0]:
0x0 : No access to boot partition (default)
0x1 : R/W boot partition 1
0x2 : R/W boot partition 2

+--------------------------------------------------------------------+
| Bit7 Bit6 Bit5 | Bit4 Bit3 | Bit2                 | Bit1 Bit0      |
|----------------|----------------------------------|----------------|
| X              | BOOT_MODE | RESET_BOOT_BUS_WIDTH | BOOT_BUS_WIDTH |
+--------------------------------------------------------------------+
Bit [4:3] : BOOT_MODE (non-volatile)
0x0 : Use single data rate + backward compatible timings in boot
operation (default)
0x1 : Use single data rate + high speed timings in boot operation mode
0x2 : Use dual data rate in boot operation
0x3 : Reserved
Bit [2]: RESET_BOOT_BUS_WIDTH (non-volatile)
0x0 : Reset bus width to x1, single data rate and backward compatible
timings after boot operation (default)
0x1 : Retain boot bus width and boot mode after boot operation
Bit[1:0] : BOOT_BUS_WIDTH (non-volatile)
0x0 : x1 (sdr) or x4 (ddr) bus width in boot operation mode (default)
0x1 : x4 (sdr/ddr) bus width in boot operation mode
0x2 : x8 (sdr/ddr) bus width in boot operation mode
0x3 : Reserved

- example of the boot_info:
boot_info:0x07;
  ALT_BOOT_MODE:1 - Supports alternate boot method
  DDR_BOOT_MODE:1 - Supports alternate dual data rate during boot
  HS_BOOTMODE:1 - Supports high speed timing during boot
boot_size:2048KB
  boot_partition:0x48;
  BOOT_ACK:1 - Boot acknowledge sent during boot operation
  BOOT_PARTITION-ENABLE: 1 - Boot partition 1 enabled
  PARTITION_ACCESS:0 - No access to boot partition
boot_bus:0x00
  BOOT_MODE:0 - Use single data rate + backward compatible timings
  in boot operation
  RESET_BOOT_BUS_WIDTH:0 - Reset bus width to x1, single data rate
  and backwardcompatible timings after boot operation
  BOOT_BUS_WIDTH:0 - x1 (sdr) or x4 (ddr) bus width in boot
  operation mode

Signed-off-by: Richard Zhu <r65037@freescale.com>