ALSA: hda/conexant: Convert to cdev-variant of mic-mute LED controls

This patch converts the remaining user of
snd_hda_gen_add_micmute_led() in Conexant codec driver into the new
snd_hda_gen_add_micmute_led_cdev().

Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Link: https://lore.kernel.org/r/20200618110842.27238-5-tiwai@suse.de


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