ASoC: Intel: Skylake: Fix to check return value of dsp init

If DSP initialization fails, ipc to disable notification
will cause NULL ptr exception as ipc is not initialized.
This patch returns error if dsp init fails before
sending disable notification ipc.

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>