ns16550: make PCI device hiding uniform

ns16550: make PCI device hiding uniform

The difference between pci_hide_device() and pci_ro_device() is that
the former only prevents a device from getting assigned to a guest,
while the latter additionally arranges for Dom0 write attempts to the
device's config space to be ignored/discarded. Whether we want one or
the other certainly doesn't depend on whether the device is in our set
of known devices. All that matters is whether we use a PCI device: Call
pci_ro_device() in any such case.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Julien Grall <julien.grall@arm.com>