drm: pass the irq explicitly to drm_irq_install

Unfortunately this requires a drm-wide change, and I didn't see a sane
way around that. Luckily it's fairly simple, we just need to inline
the respective get_irq implementation from either drm_pci.c or
drm_platform.c.

With that we can now also remove drm_dev_to_irq from drm_irq.c.

Reviewed-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index f9de156..50ec1be 100644
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -288,7 +288,7 @@
 	}
 
 	pm_runtime_get_sync(dev->dev);
-	ret = drm_irq_install(dev);
+	ret = drm_irq_install(dev, platform_get_irq(dev->platformdev, 0));
 	pm_runtime_put_sync(dev->dev);
 	if (ret < 0) {
 		dev_err(dev->dev, "failed to install IRQ handler\n");