ALSA: hda/realtek - Consolidate gpio_data and gpio_led

Until now, two fields, gpio_data and gpio_led, coexist in alc_spec
although basically both of them serve for the same purpose -- the GPIO
data bits.

This patch consolidates both usages and eliminates the superfluous
gpio_led field.

Signed-off-by: Takashi Iwai <tiwai@suse.de>