[media] rcar_vin: fix error message in rcar_vin_get_formats()

The dev_err() call is supposed to output <width>x<height> in decimal but one of
the format specifiers is "%x" instead of "%u" (most probably due  to a typo).

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>