ALSA: hda/realtek - Fix the regression by widget power-saving

While enabling the widget power-saving for ALC269 & co, the important
setup was forgotten -- stream_pm ops.  Without this setup, the paths
for PCM won't be powered up at all.

Also, the power_filter callbacks used in ALC269 & co need to chain to
the default snd_hda_gen_path_power_filter().

Tested-by: Hui Wang <hui.wang@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>