ALSA: hda/generic: Add a helper to mute speakers at suspend/shutdown

Some devices indicate click noises at suspend or shutdown when the
speakers are unmuted.  This patch adds a helper,
snd_hda_gen_shutup_speakers(), to work around it.  The new function is
supposed to be called at suspend or shutdown by the codec driver, and
it mutes the speakers.

The mute status isn't cached, hence the original mute state will be
restored at resume again.

Link: https://patch.msgid.link/20240726142625.2460-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>