arm: gic-v3-its: Rename objects

The code accesses the gic-v3 node, but not the gic-v3-its node,
thus rename the objects to clarify which node it operates on.

The following commit will make use of the gic-v3-its node for real.

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
1 file changed