mmc: jz4740: Use the new PM macros

 - Use DEFINE_SIMPLE_DEV_PM_OPS() instead of the SIMPLE_DEV_PM_OPS()
   macro. This makes it possible to remove the __maybe_unused flags
   on the callback functions.

 - Since we only have callbacks for suspend/resume, we can conditionally
   compile the dev_pm_ops structure for when CONFIG_PM_SLEEP is enabled;
   so use the pm_sleep_ptr() macro instead of pm_ptr().

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>