MdeModulePkg/Core/Dxe: Fix memory leak issue in FwVol.c

FwVolHeader must be freed on error path.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Dandan Bi <dandan.bi@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Signed-off-by: Mike Maslenkin <mike.maslenkin@gmail.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>

MdeModulePkg/Core/Dxe/FwVol/FwVol.c

@@ -659,6 +659,7 @@ NotifyFwVolBlock (
       //
       FvDevice = AllocateCopyPool (sizeof (FV_DEVICE), &mFvDevice);
       if (FvDevice == NULL) {
+        CoreFreePool (FwVolHeader);
         return;
       }