MdePkg:Add a new error status code EFI_HTTP_ERROR.

v2:
*Return the EFI_HTTP_ERROR in the “Status” field in token, instead of
in the status codes returned table of EFI_HTTP_PROTOCOL.Response() interface.

Add a new error status code EFI_HTTP_ERROR in corresponding with
the UEFI 2.6 spec

Cc: Ye Ting <ting.ye@intel.com>
Cc: Fu Siyuan <siyuan.fu@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Zhang Lubo <lubo.zhang@intel.com>
Reviewed-by: Siyuan Fu <siyuan.fu@intel.com>
Reviewed-by: Jiaxin Wu <jiaxin.wu@intel.com>

MdePkg/Include/Protocol/Http.h

@@ -282,6 +282,8 @@ typedef struct {
   /// Status will be set to one of the following value if the HTTP request is
   /// successfully sent or if an unexpected error occurs:
   ///   EFI_SUCCESS:      The HTTP request was successfully sent to the remote host.
+  ///   EFI_HTTP_ERROR:   The response message was successfully received but contains a
+  ///                     HTTP error. The response status code is returned in token.
   ///   EFI_ABORTED:      The HTTP request was cancelled by the caller and removed from
   ///                     the transmit queue.
   ///   EFI_TIMEOUT:      The HTTP request timed out before reaching the remote host.