[media] cobalt: allow fewer than 8 PCIe lanes

Currently the cobalt driver refuses to load if fewer than 8 PCIe lanes
are assigned. This patch changes this and just issues a warning. The
only time it will refuse to load is if the number of assigned lanes is less
than what the PCIe host is capable of since this suggests that the card
isn't seated correctly in the slot.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>