KVM: arm64: Make hyp_page::order a u8

We don't need 16 bits to store the hyp page order, and we'll need some
bits to store page ownership data soon, so let's reduce the order
member.

Tested-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20241218194059.3670226-4-qperret@google.com


Signed-off-by: Marc Zyngier <maz@kernel.org>