Some drivers could call serial8250_do_set_divisor() to complete its
own set_divisor routine. Export this symbol for code reusing.
Signed-off-by: NJisheng Zhang <Jisheng.Zhang@synaptics.com>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>