V4L/DVB: The first two parameters of soc_camera_limit_side() are usually pointers  to struct v4l2_rect elements. They are signed, so adjust the prototype  accordingly

This will remove the following sparse warning (see "make C=1"):

 * incorrect type in argument 1 (different signedness)
       expected unsigned int *start
       got signed int *<noident>

as well as a couple more signedness mismatches.
Signed-off-by: Márton Németh <nm127@freemail.hu>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>