ASoC: Intel: Skylake: Call i915 exit last

The Skylake driver uses i915 component APIs to talk to display.
On remove we should free up by invoking snd_hdac_i915_exit() but
that should be last thing in remove routine, so move it to last
in skl_free()

Signed-off-by: Jeeja KP <jeeja.kp@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>