sunhme: Return an ERR_PTR from quattro_pci_find

In order to differentiate between a missing bridge and an OOM condition,
return ERR_PTRs from quattro_pci_find. This also does some general linting
in the area.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>