Add functions to report the HAB (High Assurance Boot) status
of e.g. i.MX6 CPUs.
This is taken from
git://git.freescale.com/imx/uboot-imx.git branch imx_v2009.08_3.0.35_4.0.0
cpu/arm_cortexa8/mx6/generic.c
include/asm-arm/arch-mx6/mx6_secure.h
Signed-off-by: Stefano Babic <sbabic@denx.de>