ALSA: hda - Continue probing even if i915 binding fails

Currently snd-hda-intel driver aborts the probing of Intel HD-audio
controller with i915 power well management when binding with i915
driver via hda_i915_init() fails.  This is no big problem for Haswell
and Broadwell where the HD-audio controllers are dedicated to
HDMI/DP, thus i915 link is mandatory.  However, Skylake, Baytrail and
Braswell have only one controller and both HDMI/DP and analog codecs
share the same bus.  Thus, even if HDMI/DP isn't usable, we should
keep the controller working for other codecs.

For fixing this, this patch simply allows continuing the probing even
if hda_i915_init() call fails.  This may leave stale sound components
for HDMI/DP devices that are unbound with graphics.  We could abort
the probing selectively, but from the code simplicity POV, it's better
to continue in all cases.

Reported-by: Libin Yang <libin.yang@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>