media: platform: Improve the implementation of the system PM ops

Add v4l2_m2m_suspend() function call in mtk_jpeg_suspend() to make sure
that the current frame is processed completely before suspend.
Add v4l2_m2m_resume() function call in mtk_jpeg_resume() to unblock the
driver from scheduling next frame.

Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Xia Jiang <xia.jiang@mediatek.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>