drm/i915: Drop all references to DRM IRQ midlayer

Remove all references to DRM's IRQ midlayer. i915 uses Linux' interrupt
functions directly.

v2:
	* also remove an outdated comment
	* move IRQ fix into separate patch
	* update Fixes tag (Daniel)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: b318b82455 ("drm/i915: Nuke drm_driver irq vfuncs")
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: intel-gfx@lists.freedesktop.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210701173618.10718-3-tzimmermann@suse.de
(cherry picked from commit 91b96f0008)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/i915/i915_drv.c

@@ -42,7 +42,6 @@
 #include <drm/drm_aperture.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_ioctl.h>
-#include <drm/drm_irq.h>
 #include <drm/drm_managed.h>
 #include <drm/drm_probe_helper.h>
 

drivers/gpu/drm/i915/i915_irq.c

@@ -33,7 +33,6 @@
 #include <linux/sysrq.h>
 
 #include <drm/drm_drv.h>
-#include <drm/drm_irq.h>
 
 #include "display/intel_de.h"
 #include "display/intel_display_types.h"
@@ -4564,10 +4563,6 @@ void intel_runtime_pm_enable_interrupts(struct drm_i915_private *dev_priv)
 
 bool intel_irqs_enabled(struct drm_i915_private *dev_priv)
 {
-	/*
-	 * We only use drm_irq_uninstall() at unload and VT switch, so
-	 * this is the only thing we need to check.
-	 */
 	return dev_priv->runtime_pm.irqs_enabled;
 }