drm/i915/gt: Nuke gen2_irq_{enable,disable}()

We've determined that accessing the (supposedly) 16bit
interrupt registers on gen2 as 32bit works just fine.
We already dropped the special case from the main interrupt
code, do so also for the gt interrupt stuff.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241008214349.23331-2-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>