rtc: sh: Convert to DEFINE_SIMPLE_DEV_PM_OPS()

Convert the Renesas SuperH On-Chip RTC driver from SIMPLE_DEV_PM_OPS()
to DEFINE_SIMPLE_DEV_PM_OPS() and pm_sleep_ptr().  This lets us drop the
__maybe_unused annotations from its suspend and resume callbacks, and
reduces kernel size in case CONFIG_PM or CONFIG_PM_SLEEP is disabled.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/396d4a769b8d3c6fec43c65022cdfd8a6854524a.1752086758.git.geert+renesas@glider.be


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>