Now that we can use -EPROBE_DEFER, it's no longer required to spin off
the snd_hdac_i915_init into a workqueue.

Use the -EPROBE_DEFER mechanism instead, which must be returned in the
probe function.
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20231009115437.99976-11-maarten.lankhorst@linux.intel.comSigned-off-by: Takashi Iwai <tiwai@suse.de>