[media] dw2102: fix unreleased firmware

On the particular case when the product id is 0x2101 we have requested
for a firmware but after processing it we missed releasing it.

Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>