media: rcar-vin: Fix image alignment for setting pre clipping

In Video Pixel/Line Pre-Clip Register, the setting value can be
set in 1 line unit, but it can only be specified as a multiple of
4 by v4l_bound_align_image function().
So correct that it can be specified in 1 line unit with this patch.

Signed-off-by: Koji Matsuoka <koji.matsuoka.xm@renesas.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>