[media] gspca: the field 'frozen' is under CONFIG_PM

The gspca_dev field 'frozen' is added only if CONFIG_PM is set. So add the
relevant #ifdef's to various subdrivers that use it.

The m32r daily build caught this mistake.

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