Fixed initrd issue by define big RAM

Signed-off-by:Jason Jin <Jason.jin@freescale.com>

common/cmd_bootm.c

@@ -538,7 +538,6 @@ do_bootm_linux (cmd_tbl_t *cmdtp, int flag,
 			initrd_copy_to_ram = 0;
 	} else {	/* not set, no restrictions to load high */
 		initrd_high = ~0;
-		initrd_copy_to_ram = 0;
 	}
 
 #ifdef CONFIG_LOGBUFFER

include/configs/MPC8641HPCN.h

@@ -100,6 +100,7 @@
  */
 #define CFG_DDR_SDRAM_BASE	0x00000000	/* DDR is system memory*/
 #define CFG_SDRAM_BASE		CFG_DDR_SDRAM_BASE
+#define CONFIG_VERY_BIG_RAM
 
 #define MPC86xx_DDR_SDRAM_CLK_CNTL