In the unlikely case that pci_find_bus() should return NULL
viacam_serial_is_enabled() is going to dereference a NULL pointer and
blow up. Better safe than sorry, so be defensive and check the
pointer.
Signed-off-by: NJesper Juhl <jj@chaosbits.net>
Acked-by: NJonathan Corbet <corbet@lwn.net>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>