[media] MAINTAINERS: change maintainer for gscpa/pwc/radio-shark

Hans de Goede has no more time to work on those, so I'll take over.
For gspca/pwc I'll do 'Odd Fixes', for radio-shark I'll be a
full maintainer.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>