drm/xe: Drop WA 16015675438

With dynamic load-balancing disabled on the compute side, there's no
reason left to enable WA 16015675438. Drop it from both PVC and DG2.

Note that this can be done because now the driver always set a fixed
partition of EUs during initialization via the ccs_mode configuration.

Cc: Mateusz Jablonski <mateusz.jablonski@intel.com>
Cc: Michal Mrozek <michal.mrozek@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: Michal Mrozek <michal.mrozek@intel.com>
Acked-by: Mateusz Jablonski <mateusz.jablonski@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240304233103.1687412-1-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>