ALSA: hda/realtek: Limit mic boost on T480

The internal mic boost on the T480 is too high. Fix this by applying the
ALC269_FIXUP_LIMIT_INT_MIC_BOOST fixup to the machine to limit the gain.

Signed-off-by: Benjamin Berg <bberg@redhat.com>
Tested-by: Benjamin Berg <bberg@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>