V4L/DVB (11714): gspca - spca500 and sunplus: Change the 0x00 insertion mechanism.

The new mechanism does not use any temporary buffer.

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