ASoC: SOF: Intel: tgl: Add fw_regs area to debugfs map for IPC4

Expose the firmware registers via debugfs. it can be of great help while
debugging complex issues.
The area is only available with IPC4.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://msgid.link/r/20240409113349.21623-2-peter.ujfalusi@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>