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

The Thinkpad helper code is updated accordingly, too.

Also, the usage of snd_hda_gen_fixup_micmute_led() is replaced with
either the local alc_fixup_micmute_led() or the explicit call of
snd_hda_gen_add_micmute_led_cdev() with NULL callback.
Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Link: https://lore.kernel.org/r/20200618110842.27238-4-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>