drm: fixup i915 error codes

Frederik Deweerdt <deweerdt@free.fr> pointed this out, I fixed a missing
DRM error wrapper also.

Signed-off-by: Dave Airlie <airlied@linux.ie>
diff --git a/drivers/char/drm/i915_dma.c b/drivers/char/drm/i915_dma.c
index d932f80..a7924e2 100644
--- a/drivers/char/drm/i915_dma.c
+++ b/drivers/char/drm/i915_dma.c
@@ -260,7 +260,7 @@
 		retcode = i915_dma_resume(dev);
 		break;
 	default:
-		retcode = -EINVAL;
+		retcode = DRM_ERR(EINVAL);
 		break;
 	}
 
@@ -391,7 +391,7 @@
 	RING_LOCALS;
 
 	if (DRM_COPY_FROM_USER_UNCHECKED(&box, &boxes[i], sizeof(box))) {
-		return EFAULT;
+		return DRM_ERR(EFAULT);
 	}
 
 	if (box.y2 <= box.y1 || box.x2 <= box.x1 || box.y2 <= 0 || box.x2 <= 0) {