FVP AArch32: Fix flash access in BL32 for mem_protect

The FVP platform port for SP_MIN (BL32) didn't map the flash memory
in BL32 for stroring the mem_protect enable state information leading
to synchronous exception. The patch fixes it by adding the region to
the BL32 mmap tables.

Change-Id: I37eec83c3e1ea43d1b5504d3683eebc32a57eadf
Signed-off-by: Joel Hutton <Joel.Hutton@Arm.com>