drm/xe/gt: Add L3 bank mask to GT topology

Generate the mask of enabled L3 banks for the GT. It is stored with the
rest of the GT topology in a consistent representation across platforms.
For now the L3 bank mask is just printed in the log for developers to
easily figure out the fusing characteristics of machines that they are
trying to debug issues on. Later it can be used to replace existing code
in the driver that requires the L3 bank count (not mask). Also the mask
can easily be exposed to user space in a new query if needed.

v2: Better naming of variable and function (Matt Roper)

Bspec: 52545, 52546, 62482
Cc: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240410123723.7-2-francois.dugast@intel.com