OvmfPkg/XenBusDxe: fix UninstallMultipleProtocolInterfaces() call

Unlike the InstallMultipleProtocolInterfaces() boot service, which takes
an (EFI_HANDLE*) as first parameter, the
UninstallMultipleProtocolInterfaces() boot service takes an EFI_HANDLE as
first parameter.

This is an actual bug. It must have remained hidden until now because it's
on an error path. Fix the UninstallMultipleProtocolInterfaces() call.

Cc: Anthony Perard <anthony.perard@citrix.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Julien Grall <julien.grall@arm.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Reviewed-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>

OvmfPkg/XenBusDxe/XenBus.c

@@ -210,7 +210,7 @@ XenBusAddDevice (
 
 ErrorOpenProtocolByChild:
   gBS->UninstallMultipleProtocolInterfaces (
-    &Private->Handle,
+    Private->Handle,
     &gEfiDevicePathProtocolGuid, Private->DevicePath,
     &gXenBusProtocolGuid, &Private->XenBusIo,
     NULL);