pci: Toggle BAR I/O and memory space emulation

During configuration of the BAR addresses, a Linux guest disables and
enables access to I/O and memory space. When access is disabled, we don't
stop emulating the memory regions described by the BARs. Now that we have
callbacks for activating and deactivating emulation for a BAR region,
let's use that to stop emulation when access is disabled, and
re-activate it when access is re-enabled.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Link: https://lore.kernel.org/r/1589470709-4104-10-git-send-email-alexandru.elisei@arm.com


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