KVM: arm64: vgic: Remove unnecessary type castings

Remove unnecessary casts.

Signed-off-by: Yu Zhe <yuzhe@nfschina.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220329102059.268983-1-yuzhe@nfschina.com