usb: ehci-exynos: Use DEFINE_SIMPLE_DEV_PM_OPS for PM functions

This macro has the advantage over SIMPLE_DEV_PM_OPS that we don't have to
care about when the functions are actually used.

Also make use of pm_ptr() to discard all PM related stuff if CONFIG_PM
isn't enabled.

Signed-off-by: Anand Moon <linux.amoon@gmail.com>
Link: https://lore.kernel.org/r/20240412142317.5191-3-linux.amoon@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>