serial: sirf: enable ATLAS7 USP serial support

differentiate difference port types by re-defining the status MARCO
or putting HW differences into private data of the related ports.

Signed-off-by: Qipan Li <Qipan.Li@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>