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/ppc440sp.h b/arch/powerpc/include/asm/ppc440sp.h
index eb7e1d9..4387495 100644
--- a/arch/powerpc/include/asm/ppc440sp.h
+++ b/arch/powerpc/include/asm/ppc440sp.h
@@ -26,8 +26,16 @@
 /*
  * Some SoC specific registers (not common for all 440 SoC's)
  */
-#define GPIO0_BASE	(CONFIG_SYS_PERIPHERAL_BASE + 0x00000700)
+
+/* Memory mapped register */
+#define CONFIG_SYS_PERIPHERAL_BASE	0xf0000000 /* Internal Peripherals */
+
+#define CONFIG_SYS_NS16550_COM1	(CONFIG_SYS_PERIPHERAL_BASE + 0x0200)
+#define CONFIG_SYS_NS16550_COM2	(CONFIG_SYS_PERIPHERAL_BASE + 0x0300)
+
+#define GPIO0_BASE		(CONFIG_SYS_PERIPHERAL_BASE + 0x0700)
 
+/* SDR's */
 #define SDR0_PCI0	0x0300
 #define SDR0_SDSTP2	0x0022
 #define SDR0_SDSTP3	0x0023