ASoC: SOF: ipc: Only allow sending of an IPC in SOF_FW_BOOT_COMPLETE state

If the state of the firmware is not BOOT_COMPLETE, it means that the
firmware is not functioning, thus it is not capable of handling IPC
messages.
Do not try to send IPC if the state is not BOOT_COMPLETE

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/20211223113628.18582-12-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>