media: coda: V4L2_PIX_FMT_GREY for coda960 JPEG Encoder

media: coda: V4L2_PIX_FMT_GREY for coda960 JPEG Encoder

support greyscale pix fmt input for coda9_jpeg_encoder. The hardware
supports it, so allow V4L2 Mem2Mem JPEG Encoder use it as well. Tested
on an i.MX6QP.

[hverkuil: updated the Subject line as suggested by Philipp]

Signed-off-by: Martin Weber <martin.weber@br-automation.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>