drm/xe: Add debugfs to dump GuC's hwconfig

Although the query uapi is the official way to get at the GuC's hwconfig
table contents, it's still useful to have a quick debugfs interface to
dump the table in a human-readable format while debugging the driver.

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Jagmeet Randhawa <jagmeet.randhawa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240815172602.2729146-3-matthew.d.roper@intel.com