[POWERPC] Fix compile breakage for IBM/AMCC 4xx arch/ppc platforms

The IBM/AMCC 405 platforms don't compile anymore in the current
kernel version.  This fixes the compile breakage.
Signed-off-by: NStefan Roese <sr@denx.de>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

arch/ppc/syslib/ibm_ocp.c

 #include <linux/module.h>
+#include <asm/ibm4xx.h>
 #include <asm/ocp.h>
 
 struct ocp_sys_info_data ocp_sys_info = {