Fix source file permission

Change-Id: I72361f30863c49167d4a65660373e86e9283980f
diff --git a/providers/openflow/group/src/main/java/org/onosproject/provider/of/group/impl/GroupModBuilder.java b/providers/openflow/group/src/main/java/org/onosproject/provider/of/group/impl/GroupModBuilder.java
old mode 100755
new mode 100644