ASoC: SOF: Add utils

Helpers to set-up back-ends, create platform devices and common
IO/block read/write operations

Signed-off-by: Keyon Jie <yang.jie@linux.intel.com>
Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mark Brown <broonie@kernel.org>