media: imx-jpeg: Set V4L2_BUF_FLAG_LAST at eos

The V4L2_EVENT_EOS event is a deprecated behavior,
the V4L2_BUF_FLAG_LAST buffer flag should be used instead.

Signed-off-by: Ming Qian <ming.qian@nxp.com>
Reviewed-by: Mirela Rabulea <mirela.rabulea@nxp.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>