ASoC: SOF: Intel: hda-ipc: Don't read mailbox for PM_GATE reply

Memory windows could be powered off before receiving PM_GATE IPC reply
from FW, we can't read the mailbox to get reply.

Signed-off-by: Keyon Jie <yang.jie@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20191025224122.7718-15-pierre-louis.bossart@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>