tests: set MTU to 1400 on test node interfaces

In the environment we were testing on, MTU was set to 1500 which causes
download failures of our yum repos. There might be a better way to set
this instead of doing it here in ansible.

Signed-off-by: Andrew Schoen <aschoen@redhat.com>

tests/functional/rhcs_setup.yml

@@ -35,6 +35,12 @@
         group: root
       when: not is_atomic
 
+    - name: set MTU on eth0
+      command: "ifconfig eth0 mtu 1400 up"
+
+    - name: set MTU on eth1
+      command: "ifconfig eth1 mtu 1400 up"
+
 - hosts: mons
   gather_facts: false
   become: yes
@@ -65,6 +71,9 @@
       when:
         - not is_atomic
 
+    - name: set MTU on eth2
+      command: "ifconfig eth2 mtu 1400 up"
+
 - hosts: mdss:rgws:clients 
   gather_facts: false
   become: yes