Enabling Hash check to verify integrity while loading AMSS

while debugging boot related issues, few times it is required to verify the integrity of AMSS Image in RAM , to verify this we have a feature in OSBL which easies the integrity verification.

By enabling feature FEATURE_BOOT_VERIFY_AMSS_HASH in osbl_target.h, we can verify the integrity while OSBL copies AMSS to RAM , while debugging (dynamically) also we can verify this returning TRUE from function osbl_is_amss_hash_checking_required().This feature will set correct flag which enables calculation of hash of each segment while loading AMSS to RAM and compares with the pre calculated hash value..

Note:- FEATURE_BOOT_VERIFY_AMSS_HASH should not be enabled by default, as it will increase bootup time. This is a debug feature, so it shouldnot be enabled for regular/ release builds.