serial: add S3C64XX serial driver

Based on the original S3C64XX UART driver by Samsung for U-Boot 1.1.6.

Signed-off-by: Guennadi Liakhovetski <lg@denx.de>
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 2384735..f30014d 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -30,6 +30,7 @@
 COBJS-$(CONFIG_NS9750_UART) += ns9750_serial.o
 COBJS-y += ns16550.o
 COBJS-$(CONFIG_DRIVER_S3C4510_UART) += s3c4510b_uart.o
+COBJS-$(CONFIG_S3C64XX) += s3c64xx.o
 COBJS-y += serial.o
 COBJS-$(CONFIG_MAX3100_SERIAL) += serial_max3100.o
 COBJS-y += serial_pl010.o