ARM: am33xx: Inhibit re-initialization of DDR during RTC-only

This inhibits the re-inititialization of DDR during an RTC-only resume. If
this is not done, an L3 NOC error is produced as the DDR gets accessed
before the re-init has time to complete. Tested on AM437x GP EVM.

Signed-off-by: Russ Dill <Russ.Dill@ti.com>
[j-keerthy@ti.com Ported to Latest Master branch]
Signed-off-by: Keerthy <j-keerthy@ti.com>