drm/xe/irq: Drop gen3_ prefixes

"Gen" terminology should be avoided in the Xe driver and "gen3" refers
to platforms that are 9 (!!) graphics generations earlier than the
oldest supported by the Xe driver, so this prefix really doesn't make
sense.

Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20230401002106.588656-2-matthew.d.roper@intel.com


Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>