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/configuration/controllers/firmware-controller.html b/app/configuration/controllers/firmware-controller.html
index da2c397..d2ff89d 100644
--- a/app/configuration/controllers/firmware-controller.html
+++ b/app/configuration/controllers/firmware-controller.html
@@ -57,7 +57,7 @@
   <div class="modal__tftp-unreachable" role="document">
     <div class="screen-reader-offscreen modal-description">Update image priority</div><!-- accessibility only; used for screen readers -->
     <div class="page-header ">
-      <icon file="icon-warning" aria-hidden="true"></icon><span class="accessible-text" role="alert">Warning</span>
+      <icon file="icon-warning.svg" aria-hidden="true"></icon><span class="accessible-text" role="alert">Warning</span>
       <h3 class="modal-title inline">Change image priority</h3>
     </div>
     <div class="modal__content">
@@ -74,7 +74,7 @@
   <div class="modal__tftp-unreachable" role="document">
     <div class="screen-reader-offscreen modal-description">Delete firmware image</div><!-- accessibility only; used for screen readers -->
     <div class="page-header ">
-      <icon file="icon-warning" aria-hidden="true"></icon><span class="accessible-text" role="alert">Warning</span>
+      <icon file="icon-warning.svg" aria-hidden="true"></icon><span class="accessible-text" role="alert">Warning</span>
       <h3 class="modal-title inline">Delete image</h3>
     </div>
     <div class="modal__content">