media: hantro: jpeg: Add JFIF APP0 segment to JPEG encoder output

While the V4L2_PIX_FMT_JPEG format doesn't specify any requirements for
the APP0 or APP1 segments, it would be nice if the output is JFIF
compliant. While some programs can read JPEG streams that aren't, some
guess work is involved.

Add the standard JFIF APP0 segment to the JPEG header, so that the JPEG
encoder output is JFIF compliant.

Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>