MdeModulePkg/CapsuleLib: Free the buffer returned by GetVariable2 API

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>

MdeModulePkg/Library/DxeCapsuleLibFmp/DxeCapsuleReportLib.c

@@ -342,6 +342,10 @@ InitCapsuleLastVariable (
                         0,
                         NULL
                         );
+      } else {
+        if (CapsuleResult != NULL) {
+          FreePool (CapsuleResult);
+        }
       }
     }