drm/i915: fix intel_display_irq.c include order

I meant to sort the includes before submitting commit 2b874a02


("drm/i915/irq: split out display irq handling") but forgot, and it
wasn't noticed in review either. Sort the includes.

Cc: Gustavo Sousa <gustavo.sousa@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230516122926.2720581-1-jani.nikula@intel.com