To save power, the hda hdmi driver in ASoC invokes snd_hdac_ext_bus_link_put
to disable CORB/RIRB buffers DMA if there is no user of bus and invokes
snd_hdac_ext_bus_link_get to set up CORB/RIRB buffers when it is used.
Unsolicited responses is disabled in snd_hdac_bus_stop_cmd_io called by
snd_hdac_ext_bus_link_put , but it is not enabled in snd_hdac_bus_init_cmd_io
called by snd_hdac_ext_bus_link_get. So for put-get sequence, Unsolicited
responses is disabled and headphone can't be detected by hda codecs.

Now unsolicited responses is only enabled in snd_hdac_bus_reset_link
which resets controller. The function is only called for setup of
controller. This patch enables Unsolicited responses after RIRB is
initialized in snd_hdac_bus_init_cmd_io which works together with
snd_hdac_bus_reset_link to set up controller.

Tested legacy hda driver and SOF driver on intel whiskeylake.
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Rander Wang <rander.wang@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>