ALSA: hda - remove controller dependency on i915 power well for SKL

For SKL, only the HDMI codec is in the display power well while the
HD-A controller isn't. So the controller flag 'need_i915_power' is
not set to release the display power after probe, and the codec flag
'link_power_control' is set to request/release the display power via
bus link_power ops.

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