KVM: arm64: Context switch SCTLR2_ELx when advertised to the guest

Restore SCTLR2_EL1 with the correct value for the given context when
FEAT_SCTLR2 is advertised to the guest.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250708172532.1699409-13-oliver.upton@linux.dev


Signed-off-by: Oliver Upton <oliver.upton@linux.dev>