ppc: xilinx-ppc4xx-generic: Update xparameters.h

-Remove UART address (It is now part of the dts).
-Include dummy ns16550 clock
-Fix address to last test

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Acked-by: Stefan Roese <sr@denx.de>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Michal Simek <michal.simek@xilinx.com>

include/configs/xilinx-ppc.h

@@ -109,6 +109,7 @@
 #define CONFIG_SYS_BAUDRATE_TABLE	{ CONFIG_BAUDRATE }
 #else
 #ifdef XPAR_UARTNS550_0_BASEADDR
+#define CONFIG_SYS_NS16550
 #define CONFIG_SYS_NS16550_SERIAL
 #define CONFIG_SYS_NS16550_REG_SIZE	4
 #define CONFIG_CONS_INDEX		1