V4L/DVB: mx2_camera: fix for list bufnum in frame_done_emma

The emma uses bufnum 1 and 0. This patch tells the bufqueue to change
the next buffer to the next one and not the current one.
Otherwise the BUG_ON above will trigger everytime.

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>