media: iris: Fix missing LAST flag handling during drain

media: iris: Fix missing LAST flag handling during drain

Improve drain handling by ensuring the LAST flag is attached to final
capture buffer when drain response is received from the firmware.

Previously, the driver failed to attach the V4L2_BUF_FLAG_LAST flag when
a drain response was received from the firmware, relying on userspace to
mark the next queued buffer as LAST. This update fixes the issue by
checking the pending drain status, attaching the LAST flag to the
capture buffer received from the firmware (with EOS attached), and
returning it to the V4L2 layer correctly.

Fixes: d09100763bed ("media: iris: add support for drain sequence")
Cc: stable@vger.kernel.org
Reviewed-by: Vikash Garodia <quic_vgarodia@quicinc.com>
Tested-by: Vikash Garodia <quic_vgarodia@quicinc.com> # X1E80100
Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8550-HDK
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8650-HDK
Signed-off-by: Dikshita Agarwal <quic_dikshita@quicinc.com>
Tested-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org> # x1e80100-crd
Signed-off-by: Bryan O'Donoghue <bod@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>