mmc: core: Invoke sdio func driver's PM callbacks from the sdio bus

mmc: core: Invoke sdio func driver's PM callbacks from the sdio bus

The sdio func device is added to the driver model after the card
device.

This means the sdio func device will be suspend before the card device
and thus resumed after. The consequence are the mmc core don't
explicity need to protect itself from receiving sdio requests in
suspended state. Instead that can be handled from the sdio bus, which
is thus invokes the PM callbacks instead of old dummy function.

In the case were the sdio func driver don't implement the PM callbacks
the mmc core will in the early phase of system suspend, remove the
card from the driver model and thus power off it.

Cc: Aaron Lu <aaron.lu@intel.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Aaron Lu <aaron.lu@intel.com>
Tested-by: xiaoming wang <xiaoming.wang@intel.com>
Tested-by: Chuanxiao Dong <chuanxiao.dong@intel.com>
Signed-off-by: Chris Ball <chris@printf.net>