mwifiex: report error to PCIe for suspend failure

When host_sleep_config command fails, we should return an error to
PCIe, instead of continuing (and possibly panicking, when we try to keep
processing a timed-out ioctl after we return "successfully" from
suspend).

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Reviewed-by: Brian Norris <briannorris@chromium.org>
Tested-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>