MdeModulePkg/UefiBootManagerLib: Fix crash when no load options are found

Do not attempt to sort the load options when there
are none.

Signed-off-by: Jeff Brasen <jbrasen@nvidia.com>

MdeModulePkg/Library/UefiBootManagerLib/BmLoadOption.c

@@ -437,6 +437,10 @@ EfiBootManagerSortLoadOptionVariable (
 
   LoadOption = EfiBootManagerGetLoadOptions (&LoadOptionCount, OptionType);
 
+  if (LoadOptionCount == 0) {
+    return;
+  }
+
   //
   // Insertion sort algorithm
   //