ALSA: hda: Use RUNTIME_PM_OPS() and pm_ptr()

Clean up the code with the helper macros, and also assure that no PM
ops is assigned without CONFIG_PM via pm_ptr().

Merely a cleanup, there should be no actual code change.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20250313170731.26943-5-tiwai@suse.de