staging: bcm2835-camera: Fix stride on RGB3/BGR3 formats

RGB3/BGR3 end up being 3 bytes per pixel, which meant that
the alignment code ended up trying to align using bitmasking
with a mask of 96.
That doesn't work, so switch to an arithmetic alignment for
those formats.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Acked-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>