The gic_root_node variable defined in ITS driver is not actually
used, so just remove it.
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NHanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>