ARM: 8848/1: virt: Align GIC version check with arm64 counterpart

arm64 has got relaxation on GIC version check at early boot stage due
to update of the GIC architecture let's align ARM with that.

To help backports (even though the code was correct at the time of writing)
Fixes: e59941b9 ("ARM: 8527/1: virt: enable GICv3 system registers")
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>