serial: sirf: add uart receive's some error counter and mark

add overrun error's flag mark and parity's counter, we can show the
statistic from procfs node.

BTW, let the indentation of stick bits configuration look better.

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>