drm/xe/mocs: Refactor mocs/l3cc loop

There's no reason to keep the assignment an condition in the same
statement, particularly making use of the comma operator. Improve
readability by doing each step on its own statement. This will make
supporting odd number of entries more easily.

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240228061048.3661978-2-lucas.demarchi@intel.com


Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>