Use the	new DEFINE_SIMPLE_DEV_PM_OPS() instead of SIMPLE_DEV_PM_OPS()
for code-simplification.  We need no longer CONFIG_PM_SLEEP ifdefs.

For building properly, add the dummy functions for
snd_ak4531_suspend/resume() functions, too.

Just a cleanup, no functional changes.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20240207155140.18238-8-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>