plat/arm: allow RESET_TO_BL31 for CSS-based platforms

This lets any future CSS platforms to use RESET_TO_BL31 flag.

Change-Id: I32a90fce43cb0c6f4d33589653a0fd6a7ecc9577
Signed-off-by: Deepak Pandey <Deepak.Pandey@arm.com>
4 files changed