ASoC: Intel: bxtn: Store the FW/Library context at boot

Store the DSP firmware/library at boot, so that for S3 to S0 transition
use the stored ctx for downloading the firmware to DSP memory.

Signed-off-by: Jeeja KP <jeeja.kp@intel.com>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>