ASoC: Intel: Skylake: Fix kbuild dependency

The Skylake driver selects SND_HDA_I915 which causes kbuild to spew warning:

  warning: (SND_SOC_INTEL_SKYLAKE) selects SND_HDA_I915 which has unmet direct dependencies
  (SOUND && !M68K && !UML && SND && DRM_I915 && SND_HDA_CORE)

The SND_HDA_I915 should not be selected so drop that.

Reported-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>