fix(fwu): invalidate the data cache for NS_BL1U and NS_BL2U images

Invalidate the RW regions in the data cache for NS_BL1U and NS_BL2U
images before enabling MMU to safeguard against potential stale data
from previous firmware stage.

Signed-off-by: Zelalem Aweke <zelalem.aweke@arm.com>
Change-Id: Ia5fc8206685cc3c1875004f4511670d7ec07b310
6 files changed