Register PMU resources during system bootup, so that "Perf" Command can
be used to get misc performance data of a running program

The "Perf" Exe should be built manually in
"./tools/perf" using the following command line
> make CROSS_COMPILER=... ARCH=arm CFLAGS="-static -DGElf_Nhdr=Elf32_Nhdr"
then copy the "Perf" executable to rootfs/bin

Usage :
perf            # show help content
perf list       # show all available statistics options
perf stat ls    # show all statistics of a "ls" command
perf stat -e cycles tar cvfz bin.tgz /bin
                # show "cycles" statistics of command
                #     "tar cvfz ...."

MX6 Series Chips bound all CPUs PERFMON IRQ to one, this may cause some
problems when get per-CPU statistics. Need further investigation

Signed-off-by: Eric Sun <jian.sun@freescale.com>