drivers/virt: pkvm: Intercept ioremap using pKVM MMIO_GUARD hypercall

Hook up pKVM's MMIO_GUARD hypercall so that ioremap() and friends will
register the target physical address as MMIO with the hypervisor,
allowing guest exits to that page to be emulated by the host with full
syndrome information.

Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240830130150.8568-7-will@kernel.org


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