mmc: au1xmmc: use modern PM macros

mmc: au1xmmc: use modern PM macros

Use the modern PM macros for the suspend and resume functions to be
automatically dropped by the compiler when CONFIG_PM or
CONFIG_PM_SLEEP are disabled, without having to use #ifdef guards.

This has the advantage of always compiling these functions in,
independently of any Kconfig option. Thanks to that, bugs and other
regressions are subsequently easier to catch.

At the same time, replace the platform_driver's .suspend and .resume
usage with modern device_driver's .pm usage.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Link: https://lore.kernel.org/r/20250815013413.28641-9-jszhang@kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>