NetworkPkg/HttpBootDxe: Avoid the potential memory leak when eror happen.

Cc: Wang Fan <fan.wang@intel.com>
Cc: Ye Ting <ting.ye@intel.com>
Cc: Fu Siyuan <siyuan.fu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Wu Jiaxin <jiaxin.wu@intel.com>
Reviewed-by: Wang Fan <fan.wang@intel.com>

NetworkPkg/HttpBootDxe/HttpBootDhcp4.c

@@ -422,6 +422,9 @@ HttpBootParseDhcp4Packet (
     if (!IsProxyOffer) {
       OfferType = IsDnsOffer ? HttpOfferTypeDhcpDns : HttpOfferTypeDhcpOnly;
     } else {
+      if (Cache4->UriParser != NULL) {
+        FreePool (Cache4->UriParser);
+      }
       return EFI_DEVICE_ERROR;
     }
   }