bus: mhi: ep: Save channel state locally during suspend and resume

During suspend and resume, the channel state needs to be saved locally.
Otherwise, the endpoint may access the channels while they were being
suspended and causing access violations.

Fix it by saving the channel state locally during suspend and resume.

Cc: <stable@vger.kernel.org> # 5.19
Fixes: e4b7b5f0 ("bus: mhi: ep: Add support for suspending and resuming channels")
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>