[media] soc-camera: remove redundant parameter from .set_bus_param()

The "pixfmt" parameter of the struct soc_camera_host_ops::set_bus_param()
method is redundant, because at the time, when this method is called,
pixfmt is guaranteed to be equal to icd->current_fmt->host_fmt->fourcc.
Remove this parameter and update all drivers accordingly.

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