mmc: core: Attach PM domain prior probing of SDIO func driver

Other subsystem buses attach PM domains during probe, but prior calling
the driver's ->probe() method. During the removal phase, detaching the PM
domain will be done after invoking the driver's ->remove() callback.

Convert the SDIO bus to follow this behavior and add error handling.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>