pci: Use of qemu_put_ram_ptr in pci_add_option_rom.

Prevent a deadlock caused by leaving a map cache bucket locked by the
preceding qemu_get_ram_ptr() call.

Signed-off-By: John Baboval <john.baboval@virtualcomputer.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
