[ALSA] hda-codec - Fix speaker output on MacPro

Initialize the first line-out widget as the output pin in stac92xx_init().
Some devices like MacPro seem to set this widget as INPUT as default,
and confuses the driver.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>