TT#115300 GRUB templates: provide menu entry for UEFI Firmware Settings

When running in EFI mode, it's as simple as executing "fwsetup".

This is taken over from upstream change
8c0c9d9228

Change-Id: I0fffee2aa814597ade9772bd93ab6d69b1ea4f9c

templates/boot/grub/addons.cfg

@@ -21,4 +21,10 @@ submenu "Addons ->" --class=submenu {
       exit
   }
 
+if [ "${grub_platform}" == "efi" ] ; then
+  menuentry "UEFI Firmware Settings" {
+      fwsetup
+  }
+fi
+
 }