[media] gspca_main: Allow switching from read to mmap / userptr mode

Some applications (xawtv, qv4l2) mix read and mmap calls. Allow switching
from read mode back to mmap mode (by doing a reqbufs).

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Jean-Francois Moine <moinejf@free.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
1 file changed