The SGI platform defines the macro PLAT_ARM_MEM_PROT_ADDR which
indicates that the platform has mitigation for cold reboot attacks.

However, the flash memory used for the mem_protect region was not
mapped. This results in a crash when an OS calls PSCI MEM_PROTECT.

To fix this map the flash region used for mem_protect.

Change-Id: Ia494f924ecfe2ce835c045689ba8f942bf0941f4
Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>