fix(gic): don't access a GIC register if it's not supported

On non-gicv3 systems, this register will not be present. However, the
check for gicv3 wil be after, resulting in an error.

Change-Id: I6077289eb848bd3194660f975baeca5141b14e1f
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
1 file changed