drm: fix irq naming for kms drivers.

allocating devname in the i915 driver was a hack originally and I
forgot to figure out how to do this properly back then.

So this is the cleaner version that just picks devname or driver name
in the irq code.

It removes the devname allocs from the i915 driver.

Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 53d5445..0ccb63e 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -987,12 +987,6 @@
 	int fb_bar = IS_I9XX(dev) ? 2 : 0;
 	int ret = 0;
 
-	dev->devname = kstrdup(DRIVER_NAME, GFP_KERNEL);
-	if (!dev->devname) {
-		ret = -ENOMEM;
-		goto out;
-	}
-
 	dev->mode_config.fb_base = drm_get_resource_start(dev, fb_bar) &
 		0xff000000;
 
@@ -1006,7 +1000,7 @@
 
 	ret = i915_probe_agp(dev, &agp_size, &prealloc_size);
 	if (ret)
-		goto kfree_devname;
+		goto out;
 
 	/* Basic memrange allocator for stolen space (aka vram) */
 	drm_mm_init(&dev_priv->vram, 0, prealloc_size);
@@ -1024,7 +1018,7 @@
 
 	ret = i915_gem_init_ringbuffer(dev);
 	if (ret)
-		goto kfree_devname;
+		goto out;
 
 	/* Allow hardware batchbuffers unless told otherwise.
 	 */
@@ -1056,8 +1050,6 @@
 
 destroy_ringbuffer:
 	i915_gem_cleanup_ringbuffer(dev);
-kfree_devname:
-	kfree(dev->devname);
 out:
 	return ret;
 }