execute kernel mod change as root

Change-Id: I4157962c227e1d1477fc4faccb3b3e2b003daf2e
(cherry picked from commit ffff712f7f9fd356cc72db881d00bbb92330f92d)
diff --git a/roles/compute-node/tasks/mlnx_driver.yml b/roles/compute-node/tasks/mlnx_driver.yml
index 728ebb4..ef73871 100644
--- a/roles/compute-node/tasks/mlnx_driver.yml
+++ b/roles/compute-node/tasks/mlnx_driver.yml
@@ -52,6 +52,7 @@
   changed_when: true
 
 - name: Load mlnx Driver
+  become: yes
   command: /etc/init.d/mlnx-en.d restart
   changed_when: true