ALSA: hda/realtek - Update Initial AMP for EAPD control

The default EAPD control uses verb command to control EAPD. Some codec
does not have verb command for EAPD. It needs to control by hidden
register.

This update will avoid wrong behavior for some codec.  This patch will
fix double setup for EAPD.  It just needs to turn on by one site for
verb command or hidden register controlled.

Detailed changes:
- alc889_coef_init() is replaced with alc_update_coef_idx() with a
  correct COEF value.
- for ALC262, ALC887 and ALC900, the EAPD setup via the hidden
  register is removed because this rather conflicts with the EAPD verb
  setup.
-  For ALC888-VC, also the hidden register access is removed in
  alc888_coef_init().
- Remove the dead #if 0 code for ALC267/ALC268.

Signed-off-by: Kailang Yang <kailang@realtek.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>