GPU-DRM: Replace a kzalloc() call by kcalloc() in drm_legacy_addbufs_sg()

The script "checkpatch.pl" can point information out like the following.

WARNING: Prefer kcalloc over kzalloc with multiply

Thus fix the affected source code place.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/b340d1ca-f114-a523-e6d1-afe7fd6c3826@users.sourceforge.net

drivers/gpu/drm/drm_bufs.c

@@ -1117,8 +1117,7 @@ static int drm_legacy_addbufs_sg(struct drm_device *dev,
 		return -EINVAL;
 	}
 
-	entry->buflist = kzalloc(count * sizeof(*entry->buflist),
-				GFP_KERNEL);
+	entry->buflist = kcalloc(count, sizeof(*entry->buflist), GFP_KERNEL);
 	if (!entry->buflist) {
 		mutex_unlock(&dev->struct_mutex);
 		atomic_dec(&dev->buf_alloc);