ramips: add a baurate hack

When talking to an atmel controller we need 9600 or 250000 baud.
as 250000 does not exist we use 2500000.

Signed-off-by: John Crispin <blogic@openwrt.org>

SVN-Revision: 47204

target/linux/ramips/patches-3.18/0304-baud_250000.patch

@@ -0,0 +1,12 @@
+--- a/drivers/tty/serial/serial_core.c
++++ b/drivers/tty/serial/serial_core.c
+@@ -356,6 +356,9 @@
+ 	else if (flags == UPF_SPD_WARP)
+ 		altbaud = 460800;
+ 
++	if (tty_termios_baud_rate(termios) == 2500000)
++		return 250000;
++
+ 	for (try = 0; try < 2; try++) {
+ 		baud = tty_termios_baud_rate(termios);
+