drm: omapdrm: Simplify IRQ registration

The omapdrm can't use drm_irq_install() and drm_irq_uninstall() as it
delegates IRQ handling to the omapdss driver. However, the code still
declares IRQ-related operations used by the DRM IRQ helpers, and calls
them indirectly.

Simplify the implementation by calling the functions directly or
inlining them. The irq_enabled checks can then also be simplified as
the call stacks guarantees that omap_drm_irq_install() and
omap_drm_irq_uninstall() will never run concurrently.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/gpu/drm/omapdrm/omap_drv.h b/drivers/gpu/drm/omapdrm/omap_drv.h
index 6c0cb46..f1005b4 100644
--- a/drivers/gpu/drm/omapdrm/omap_drv.h
+++ b/drivers/gpu/drm/omapdrm/omap_drv.h
@@ -122,15 +122,11 @@
 
 int omap_irq_enable_vblank(struct drm_device *dev, int crtc_id);
 void omap_irq_disable_vblank(struct drm_device *dev, int crtc_id);
-irqreturn_t omap_irq_handler(int irq, void *arg);
-void omap_irq_preinstall(struct drm_device *dev);
-int omap_irq_postinstall(struct drm_device *dev);
-void omap_irq_uninstall(struct drm_device *dev);
 void __omap_irq_register(struct drm_device *dev, struct omap_drm_irq *irq);
 void __omap_irq_unregister(struct drm_device *dev, struct omap_drm_irq *irq);
 void omap_irq_register(struct drm_device *dev, struct omap_drm_irq *irq);
 void omap_irq_unregister(struct drm_device *dev, struct omap_drm_irq *irq);
-int omap_drm_irq_uninstall(struct drm_device *dev);
+void omap_drm_irq_uninstall(struct drm_device *dev);
 int omap_drm_irq_install(struct drm_device *dev);
 
 struct drm_fb_helper *omap_fbdev_init(struct drm_device *dev);