Currently, use CONFIG_MX6_INTER_LDO_BYPASS to enable/disable LDO bypass, and
use the same macro in u-boot too. It's not very friendly ,it will be more
flexible if use dynamic configure by command line input by u-boot.
Two ways to enable LDO bypass:
1. use command line:
You can set "ldo_active=on" or "ldo_active=off" in command line to enable/
disable LDO bypass.
2. set enable_ldo_mode value in board file:
If you didn't set the param in command line, every board
will use its default value, for example, you can find below code in arch/arm/
mach-mx6/mx6q_sabresd_pmic_pfuze100.c:
static int pfuze100_init(struct mc_pfuze *pfuze)
{
	        ....
		        /*use default mode(ldo bypass) if no param from cmdline*/
			        if (enable_ldo_mode == LDO_MODE_DEFAULT)
					                enable_ldo_mode = LDO_MODE_BYPASSED;
							        ....
}

Note:
1.You should know clearly ldo bypass can be only enabled in the board
that mounted with external pmic to supply VDDARM_IN/VDDSOC_IN power rail, and
you should implement related external regulator firstly, such as:
in arch/arm/mach-mx6/board-mx6q_sabresd.c
static struct mxc_dvfs_platform_data sabresd_dvfscore_data = {
	                .reg_id = "VDDCORE",
			                .soc_id = "VDDSOC",
					                ....
}
otherwise, you have to use internal ldo which is the default configuration.
2.one special case, if the chip is 1.2Ghz, it can't be set LDO bypass.

Signed-off-by: Robin Gong <b38343@freescale.com>