ALSA: hda/hdmi: fix max DP-MST dev_num for Intel TGL+ platforms

Increase the device select range to 4 on platforms supporting
4 concurrent displays.

This fixes a problem in scenario where total of 4 displays are active,
and 3 of these are audio capable DP receivers and connected to a DP-MST
hub. Due to incorrect range for device select, audio could not be played
to the 3rd monitor in DP-MST hub.

BugLink: https://github.com/thesofproject/linux/issues/2798
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Link: https://lore.kernel.org/r/20210324172337.51730-1-kai.vehmanen@linux.intel.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>