ppc4xx: Fix problem with CONFIG_MAX_MEM_MAPPED in include/asm-ppc/config.h

CONFIG_SDRAM_PPC4xx_IBM_DDR2 is not set when include/asm-ppc/config.h is
included. So for katmai, CONFIG_MAX_MEM_MAPPED will get set to 256MB.

It makes perfect sense to set CONFIG_MAX_MEM_MAPPED to 2GB for all PPC4xx
boards right now.

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/include/asm-ppc/config.h b/include/asm-ppc/config.h
index 6d27cb1..2a4ee15 100644
--- a/include/asm-ppc/config.h
+++ b/include/asm-ppc/config.h
@@ -22,10 +22,10 @@
 #define _ASM_CONFIG_H_
 
 #ifndef CONFIG_MAX_MEM_MAPPED
-#if defined(CONFIG_SDRAM_PPC4xx_IBM_DDR2) && defined(CONFIG_SPD_EEPROM)
+#if defined(CONFIG_4xx)
 #define CONFIG_MAX_MEM_MAPPED	((phys_size_t)2 << 30)
 #else
-#define CONFIG_MAX_MEM_MAPPED (256 << 20)
+#define CONFIG_MAX_MEM_MAPPED	(256 << 20)
 #endif
 #endif