usb: gadget: pch_udc: Remove CONFIG_PM_SLEEP ifdefery

Use __maybe_unused for the suspend()/resume() hooks and get rid of
the CONFIG_PM_SLEEP ifdefery to improve the code.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210325135508.70350-2-andriy.shevchenko@linux.intel.com


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