ARM: S5P64X0: Add UART serial support for S5P6450

This patch adds UART serial port support for S5P6450 SoC.
The S5P6450 has 6 UARTs, so adds resource of UART4 and UART5.
And to fix membase which is in serial/samsung.c is from Ben Dooks.

Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Cc: Ben Dooks <ben-linux@fluff.org>
diff --git a/drivers/serial/samsung.c b/drivers/serial/samsung.c
index b1156ba..7ac2bf5 100644
--- a/drivers/serial/samsung.c
+++ b/drivers/serial/samsung.c
@@ -1101,7 +1101,7 @@
 	dbg("resource %p (%lx..%lx)\n", res, res->start, res->end);
 
 	port->mapbase = res->start;
-	port->membase = S3C_VA_UART + res->start - (S3C_PA_UART & 0xfff00000);
+	port->membase = S3C_VA_UART + (res->start & 0xfffff);
 	ret = platform_get_irq(platdev, 0);
 	if (ret < 0)
 		port->irq = 0;