ppc4xx: Use common NS16550 driver for PPC4xx UART

This patch removes the PPC4xx UART driver. Instead the common NS16550
driver is used, since all PPC4xx SoC's use this peripheral device.

The file 4xx_uart.c now only implements the UART clock calculation
function which also sets the SoC internal UART divisors.

All PPC4xx board config headers are changed to use this common NS16550
driver now.

Tested on these boards:
acadia, canyonlands, katmai, kilauea, sequoia, zeus

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/arch/powerpc/include/asm/ppc460ex_gt.h b/arch/powerpc/include/asm/ppc460ex_gt.h
index 04c3fbe..732fcac 100644
--- a/arch/powerpc/include/asm/ppc460ex_gt.h
+++ b/arch/powerpc/include/asm/ppc460ex_gt.h
@@ -29,8 +29,16 @@
  * Some SoC specific registers
  */
 
-#define GPIO0_BASE		(CONFIG_SYS_PERIPHERAL_BASE + 0x00000B00)
-#define GPIO1_BASE		(CONFIG_SYS_PERIPHERAL_BASE + 0x00000C00)
+/* Memory mapped registers */
+#define CONFIG_SYS_PERIPHERAL_BASE	0xef600000 /* Internal Peripherals */
+
+#define CONFIG_SYS_NS16550_COM1	(CONFIG_SYS_PERIPHERAL_BASE + 0x0300)
+#define CONFIG_SYS_NS16550_COM2	(CONFIG_SYS_PERIPHERAL_BASE + 0x0400)
+#define CONFIG_SYS_NS16550_COM3	(CONFIG_SYS_PERIPHERAL_BASE + 0x0500)
+#define CONFIG_SYS_NS16550_COM4	(CONFIG_SYS_PERIPHERAL_BASE + 0x0600)
+
+#define GPIO0_BASE		(CONFIG_SYS_PERIPHERAL_BASE + 0x0b00)
+#define GPIO1_BASE		(CONFIG_SYS_PERIPHERAL_BASE + 0x0c00)
 
 /* DCR */
 #define AHB_TOP			0x00a4