IO_LIMIT and IO_BASE registers should not be writable if
gen_pcie_root_port's io-reserve property is set to 0.
The COMMAND register should have the IO flag read only.
Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>