ppc4xx: Consolidate some of the 405 and 440 macros/structs into 4xx

This patch moves some common 4xx macros and the PPC405_SYS_INFO/
PPC440_SYS_INFO structure into the common ppc4xx.h header.

Lot's of other macros are good candidates to be consolidated this way
in the future.

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/board/xilinx/ml300/ml300.c b/board/xilinx/ml300/ml300.c
index 60f0bc2..58bfac0 100644
--- a/board/xilinx/ml300/ml300.c
+++ b/board/xilinx/ml300/ml300.c
@@ -108,7 +108,7 @@
 get_PCI_freq(void)
 {
 	ulong val;
-	PPC405_SYS_INFO sys_info;
+	PPC4xx_SYS_INFO sys_info;
 
 	get_sys_info(&sys_info);
 	val = sys_info.freqPCI;