serial: xilinx_uartps: set_mctrl sets RTS and DTR

set_mctrl now sets RTS and DTR.

Signed-off-by: Maarten Brock <m.brock@vanmierlo.com>
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
Link: https://lore.kernel.org/r/1574687731-21563-3-git-send-email-shubhrajyoti.datta@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>