main:     Change the packet copy mechanism for userptr.
          Cannot do reqbufs ioctl when already done and count != 0.
          Accept count < frame size in read().
Signed-off-by: NJean-Francois Moine <moinejf@free.fr>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>