drm/i915: Nuke drm_driver irq vfuncs

Stop using the irq vfuncs under drm_driver. That's not going to fly
in a mixed gen environment since the structure is shared between all
the devices.

v2: Allow intel_irq_uninstall() to be called twice due to
    intel_modeset_cleanup() calling it as well. Toss in a
    FIXME to remind us that this is not great.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190620103334.15651-1-ville.syrjala@linux.intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/i915_drv.c

@@ -756,7 +756,7 @@ cleanup_gem:
 cleanup_modeset:
 	intel_modeset_cleanup(dev);
 cleanup_irq:
-	drm_irq_uninstall(dev);
+	intel_irq_uninstall(dev_priv);
 	intel_gmbus_teardown(dev_priv);
 cleanup_csr:
 	intel_csr_ucode_fini(dev_priv);