bus: mhi: ep: Only send -ENOTCONN status if client driver is available

For the STOP and RESET commands, only send the channel disconnect status
-ENOTCONN if client driver is available. Otherwise, it will result in
null pointer dereference.

Cc: <stable@vger.kernel.org> # 5.19
Fixes: e8275690 ("bus: mhi: ep: Add support for processing command rings")
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Link: https://lore.kernel.org/r/20221228161704.255268-4-manivannan.sadhasivam@linaro.org


Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>