serial: imx: Remove return value from imx_setup_ufcr()

The return value from imx_setup_ufcr() is always 0 and its value is never
checked, so better to remove the return value.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>