fix cub (#7079)

diff --git a/.gitmodules b/.gitmodules
index 08f2bc9..0f36f8f 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -12,5 +12,5 @@
 	url = https://github.com/dmlc/nnvm
 [submodule "cub"]
 	path = cub
-	url = https://github.com/NVlabs/cub
+	url = https://github.com/dmlc/cub
   shallow=true
diff --git a/cub b/cub
index 89de7ab..a50619b 160000
--- a/cub
+++ b/cub
@@ -1 +1 @@
-Subproject commit 89de7ab20167909bc2c4f8acd397671c47cf3c0d
+Subproject commit a50619b006fc753b8eb4cfccdea17698cba40d5e