ASoC: Intel: Skylake: Acquire irq after RIRB allocation

Cold reboot stress test found that the hda irq could access rirb ring
buffer before its memory gets allocated which resulting in null
pointer dereference inside snd_hdac_bus_update_rirb().

Fix it by moving the skl_acquire_irq after ring buffer allocation.
While here, also change err return from -EBUSY to actual error code.

Signed-off-by: Yong Zhi <yong.zhi@intel.com>
Acked-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>