scp/dmc620: Skip binding to DDR module if it's not present

Created by: anukou

The assumption that a DMC module config would always have a valid DDR PHY isn't always correct, for instance, in FVP environment(s). Bypass binding to and configuring a DDR module if such is the case.

Change-Id: I82c7cada74bc89848dae8361a1d39565e9361c9c Signed-off-by: Anurag Koul anurag.koul@arm.com