KVM: arm64: Use the correct timer structure to access the physical counter

Use the physical timer structure when reading the physical counter
instead of using the virtual timer structure. Thankfully, nothing is
accessing this code path yet (at least not until we enable save/restore
of the physical counter). It doesn't hurt for this to be correct though.

Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de>
[maz: amended commit log]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Fixes: 84135d3d ("KVM: arm/arm64: consolidate arch timer trap handlers")
Link: https://lore.kernel.org/r/1584351546-5018-1-git-send-email-karahmed@amazon.de