[media] gspca - sn9c20x: Cleanup source

- copyright change
- use the kbuild module name for messages
- remove useless code
- add/remove blank lines, parenthesis, braces
- add/change some information messages

Signed-off-by: Jean-François Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>