BaseTools: add capsule image header for auth FMP capsule file

in last commit 91ae29, it missed to add the
EFI_FIRMWARE_MANAGEMENT_CAPSULE_IMAGE_HEADER for the auth FMP capsule.

Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Yonghong Zhu <yonghong.zhu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

BaseTools/Source/Python/GenFds/CapsuleData.py

@@ -216,14 +216,4 @@ class CapsulePayload(CapsuleData):
                        VendorFileSize,
                        int(self.HardwareInstance, 16)
                        )
-        #
-        # Append file content to the structure
-        #
-        ImageFile = open(self.ImageFile, 'rb')
-        Buffer += ImageFile.read()
-        ImageFile.close()
-        if self.VendorCodeFile:
-            VendorFile = open(self.VendorCodeFile, 'rb')
-            Buffer += VendorFile.read()
-            VendorFile.close()
         return Buffer