Fix icon-warning syntax error

There were a few instances of the icon-warning icon that didn't
include the file extenstion needed to when adding the file attribute
property in the icon directive.

Signed-off-by: Derick Montague <derick.montague@ibm.com>
Change-Id: Ib25c28c72285fa214f75258b0b09790d52bb6cc1
diff --git a/app/server-control/controllers/power-operations-modal.html b/app/server-control/controllers/power-operations-modal.html
index 1d5387f..e8c9197 100644
--- a/app/server-control/controllers/power-operations-modal.html
+++ b/app/server-control/controllers/power-operations-modal.html
@@ -10,7 +10,7 @@
   </button>
   <div class="modal-header" id="modal-operation">
     <h3>
-      <icon file="icon-warning" aria-hidden="true"></icon>
+      <icon file="icon-warning.svg" aria-hidden="true"></icon>
       {{
         activeModal === 2 || activeModal === 3
           ? "Server shutdown will cause outage"