This patch allows the ARM Platforms to specify the TZC regions to be
specified to the ARM TZC helpers in arm_tzc400.c and arm_tzc_dmc500.c.
If the regions are not specified then the default TZC region will be
configured by these helpers.

This override mechanism allows specifying special regions for TZMP1
usecase.
Signed-off-by: Summer Qin <summer.qin@arm.com>