arm64: Fix comments in macro __init_el2_gicv3

Fix typo in comment.

Signed-off-by: Zhiyuan Dai <daizhiyuan@phytium.com.cn>
Link: https://lore.kernel.org/r/1647831387-3686-1-git-send-email-daizhiyuan@phytium.com.cn


Signed-off-by: Will Deacon <will@kernel.org>