drm/xe/irq: Split irq mask per engine class

drm/xe/irq: Split irq mask per engine class

Each engine class has a different bitfield structure in the hw. We've
been just using a common mask for all of them, but this means that we
could inadvertently set a wrong bit in one class while enabling
something in another. Split them to make it more future proof.

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20251016-xe3p-v3-18-3dd173a3097a@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>