trusty: Allow getting trusty memsize from BL32_MEM_SIZE instead of TSP_SEC_MEM_SIZE
trusty: Allow getting trusty memsize from BL32_MEM_SIZE instead of TSP_SEC_MEM_SIZE

Some platforms define BL32_MEM_SIZE instead of TSP_SEC_MEM_SIZE, but
the meaning is the same.

Change-Id: I93d96dca442e653435cae6a165b1955efe2d2b75
Signed-off-by: Arve Hjønnevåg <203686835f49d1750fcbb70065cda5c503139a61@android.com>

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware