ASoC: Intel: Update Baytrail ADSP firmware name

Update the initial Baytrail ADSP firmware file name with the one that is now
in linux-firmware.git. Please see linux-firmware.git commit 7551a3a78453
("fw_sst_0f28: Add firmware for Intel Baytrail SST DSP").

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Mark Brown <broonie@linaro.org>