Build: Validate metadata from flash by default

Sets both ITS_VALIDATE_METADATA_FROM_FLASH and
PS_VALIDATE_METADATA_FROM_FLASH to ON by default,
restoring previous behaviour.

Change-Id: Ic85a6b4d615e0aad6a4d99f8f0f040e8fbee1718
Signed-off-by: Jamie Fox <jamie.fox@arm.com>
1 file changed