media: hantro: jpeg: Add COM segment to JPEG header to align image scan

The JPEG header size is not 64-bit aligned. This makes the driver
require a bounce buffer for the encoded JPEG image scan output.

Add a COM (comment) segment to the JPEG header so that the header size
is a multiple of 64 bits. This will then allow dropping the use of the
bounce buffer, and instead have the hardware write out to the capture
buffer directly.

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>