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

The existing 'tplg_path' module parameter can be used to load
alternate firmware files, be it for development or to handle
OEM-specific or board-specific releases. However the topology filename
is either hard-coded in machine descriptors or modified by specific
DMI-quirks.

For additional flexibility, this patch adds the 'tplg_filename' module
parameter to override topology names.

To avoid any confusion between DMI- and parameter-override, a variable
rename is added.

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/20220414184817.362215-7-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>