ALSA: hda/conexant: Always enable the headset-mic pin on plugin

Rename the function to cx_process_headset_detect_plug_type() to reflect
that it only reports the detected plug type, and move the pin control
write into cx_update_headset_mic_vref() so that node 0x19 is always set
to enable the headset mic with the 80% VREF whenever the mic is
present, regardless of the type detection result.

Signed-off-by: Bob Song <songxiebing@kylinos.cn>
Link: https://patch.msgid.link/20260826115344.2128835-1-songxiebing@kylinos.cn
Signed-off-by: Takashi Iwai <tiwai@suse.de>