Set NS version SCTLR during warmboot path

Set NS version SCTLR during warmboot path

When ARM TF executes in AArch32 state, the NS version of SCTLR
is not being set during warmboot flow. This results in secondary
CPUs entering the Non-secure world with the default reset value
in SCTLR.

This patch explicitly sets the value of the NS version of SCTLR
during the warmboot flow rather than relying on the h/w.

Change-Id: I86bf52b6294baae0a5bd8af0cd0358cc4f55c416
Signed-off-by: David Cunado <david.cunado@arm.com>