BaseTools: replace get_bytes_le() to bytes_le

UUID does not have the get_bytes_le() in python3

Cc: Bob Feng <bob.c.feng@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Yonghong Zhu <yonghong.zhu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Zhiju.Fan <zhijux.fan@intel.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Liming Gao <liming.gao@intel.com>
Reviewed-by: Bob Feng <bob.c.feng@intel.com>

BaseTools/Source/Python/GenFds/CapsuleData.py

@@ -229,7 +229,7 @@ class CapsulePayload(CapsuleData):
                        )
         if AuthData:
             Buffer += pack('QIHH', AuthData[0], AuthData[1], AuthData[2], AuthData[3])
-            Buffer += uuid.UUID(AuthData[4]).get_bytes_le()
+            Buffer += uuid.UUID(AuthData[4]).bytes_le
 
         #
         # Append file content to the structure