drm: Kill DRM_SUSER

Checking directly for the right capability is simpler. Also this rids
us of a few places that use DRM_CURRENTPID.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/via/via_dma.c b/drivers/gpu/drm/via/via_dma.c
index 5d41792..a18479c 100644
--- a/drivers/gpu/drm/via/via_dma.c
+++ b/drivers/gpu/drm/via/via_dma.c
@@ -234,13 +234,13 @@
 
 	switch (init->func) {
 	case VIA_INIT_DMA:
-		if (!DRM_SUSER(DRM_CURPROC))
+		if (!capable(CAP_SYS_ADMIN))
 			retcode = -EPERM;
 		else
 			retcode = via_initialize(dev, dev_priv, init);
 		break;
 	case VIA_CLEANUP_DMA:
-		if (!DRM_SUSER(DRM_CURPROC))
+		if (!capable(CAP_SYS_ADMIN))
 			retcode = -EPERM;
 		else
 			retcode = via_dma_cleanup(dev);