snd_hdac_link_power() has to be called after unregistering the codec
device.  Otherwise the device might be already runtime-suspended, thus
the refcount goes under zero, triggering a warning like:

  WARNING: CPU: 7 PID: 2014 at sound/hda/hdac_i915.c:63 snd_hdac_display_power+0x106/0x120 [snd_hda_core]()
  CPU: 7 PID: 2014 Comm: modprobe Not tainted 4.1.0-rc7-test+ #1
  Call Trace:
   [<ffffffff81697fe3>] dump_stack+0x4c/0x6e
   [<ffffffff810696da>] warn_slowpath_common+0x8a/0xc0
   [<ffffffff810697ca>] warn_slowpath_null+0x1a/0x20
   [<ffffffffa02dd526>] snd_hdac_display_power+0x106/0x120 [snd_hda_core]
   [<ffffffffa030b422>] azx_intel_link_power+0x12/0x20 [snd_hda_intel]
   [<ffffffffa037139f>] azx_link_power+0x1f/0x30 [snd_hda_codec]
   [<ffffffffa02d89fe>] snd_hdac_link_power+0x2e/0x40 [snd_hda_core]
   [<ffffffffa0368524>] snd_hda_codec_dev_free+0x34/0x50 [snd_hda_codec]
   [<ffffffffa0252061>] __snd_device_free+0x51/0xa0 [snd]
   .....
Signed-off-by: Takashi Iwai <tiwai@suse.de>