staging: android: ion: Remove ret variable in ion_handle_put_nolock

It is not necessary to save the return value of kref_put since it is directly
returned.

Signed-off-by: Johanna Abrahamsson <johanna@mjao.org>
Acked-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>