Fix an inconsistently named variable

roles/mount_device/molecule/default/converge.yml

@@ -18,7 +18,7 @@
 
   roles:
     - role: genlab.common.mount_device
-      devices:
+      mount_device_devices:
         - what: "/tmp/test_file"
           where: "/test_mount"
           fstype: ext3

roles/mount_device/tasks/main.yml

@@ -1,6 +1,6 @@
 ---
 - name: "Mount devices"
-  with_items: "{{ devices }}"
+  loop: "{{ mount_device_devices }}"
   ansible.posix.mount:
     fstype: "{{ item.fstype }}"
     path: "{{ item.where }}"