media: iris: gen2: Add sanity check for session stop

media: iris: gen2: Add sanity check for session stop

In iris_kill_session, inst->state is set to IRIS_INST_ERROR and
session_close is executed, which will kfree(inst_hfi_gen2->packet).
If stop_streaming is called afterward, it will cause a crash.

Add a NULL check for inst_hfi_gen2->packet before sendling STOP packet
to firmware to fix that.

Fixes: 11712ce70f8e ("media: iris: implement vb2 streaming ops")
Signed-off-by: Dikshita Agarwal <dikshita.agarwal@oss.qualcomm.com>
Reviewed-by: Vikash Garodia <vikash.garodia@oss.qualcomm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Bryan O'Donoghue <bod@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>