ALSA: hda/realtek - Avoid bogus HP-pin assignment

When the headphone pin is assigned as primary output to line_out_pins[],
the automatic HP-pin assignment by ASSID must be suppressed.  Otherwise
a wrong pin might be assigned to the headphone and breaks the auto-mute.

Reference: https://bugzilla.novell.com/show_bug.cgi?id=716104

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Cc: <stable@kernel.org>