V4L/DVB (10672): sh_mobile_ceu_camera: include NV* formats into the format list only once.

Currently, if an soc-camera device, connected to the sh_mobile_ceu_camera
camera host driver, supports several formats from the UYVY, VYUY, YUYV, YVYU
set, the driver would add four NV* formats for each of them. This patch fixes
this misbehaviour.

Reported-by: Kuninori Morimoto <morimoto.kuninori@renesas.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>