ASoC: SOF: sof-pci-dev: add parameter to override firmware filename

The existing 'fw_path' module parameter can be used to load alternate
firmware files, be it for development or to handle OEM-specific or
board-specific releases. The firmware name is however non-modifiable
and defined by platform-specific descriptors.

For additional flexibility during development or enable quirks, this
patch adds the 'fw_filename' module parameter to override default
firmware names.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Daniel Baluta <daniel.baluta@nxp.com>
Reviewed-by: Paul Olaru <paul.olaru@oss.nxp.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20220414184817.362215-6-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>