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.c b/drivers/gpu/drm/omapdrm/omap_drv.c
index bf02121..47fb99b 100644
--- a/drivers/gpu/drm/omapdrm/omap_drv.c
+++ b/drivers/gpu/drm/omapdrm/omap_drv.c
@@ -656,8 +656,7 @@
 };
 
 static struct drm_driver omap_drm_driver = {
-	.driver_features = DRIVER_HAVE_IRQ | DRIVER_MODESET | DRIVER_GEM
-			 | DRIVER_PRIME,
+	.driver_features = DRIVER_MODESET | DRIVER_GEM  | DRIVER_PRIME,
 	.load = dev_load,
 	.unload = dev_unload,
 	.open = dev_open,
@@ -668,10 +667,6 @@
 	.get_vblank_counter = drm_vblank_count,
 	.enable_vblank = omap_irq_enable_vblank,
 	.disable_vblank = omap_irq_disable_vblank,
-	.irq_preinstall = omap_irq_preinstall,
-	.irq_postinstall = omap_irq_postinstall,
-	.irq_uninstall = omap_irq_uninstall,
-	.irq_handler = omap_irq_handler,
 #ifdef CONFIG_DEBUG_FS
 	.debugfs_init = omap_debugfs_init,
 	.debugfs_cleanup = omap_debugfs_cleanup,