ASoC: Intel: atom: save FW version

After the boot of the SST FW the firmware version is send back
to the driver. This patch is saving the FW version inside the
driver.

Signed-off-by: Sebastien Guiriec <sebastien.guiriec@intel.com>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>