ASoC: SOF: Rename 'enum snd_sof_fw_state' to 'enum sof_fw_state'

Since there is nothing SND about the firmware state, rename the enum
from `snd_sof_fw_state` to simply `sof_fw_state`

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Paul Olaru <paul.olaru@oss.nxp.com>
Link: https://lore.kernel.org/r/20211223113628.18582-11-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>