mips: mtmips: change baudrate table for all boards

This patch changes baudrate table for all boards preparing for using mtk
highspeed uart driver.

Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
diff --git a/include/configs/gardena-smart-gateway-mt7688.h b/include/configs/gardena-smart-gateway-mt7688.h
index b3b89d2..e83a96a 100644
--- a/include/configs/gardena-smart-gateway-mt7688.h
+++ b/include/configs/gardena-smart-gateway-mt7688.h
@@ -22,7 +22,7 @@
 
 /* UART */
 #define CONFIG_SYS_BAUDRATE_TABLE	{ 9600, 19200, 38400, 57600, 115200, \
-					  230400, 500000, 1500000 }
+					  230400, 460800, 921600 }
 
 /* RAM */
 #define CONFIG_SYS_MEMTEST_START	0x80100000