Fix compilation error for TASREG

TASREG is ColdFire platform, the include ppc4xx.h in
board/esd/common/flash.c causes conflict.
Signed-off-by: NTsiChung Liew <Tsi-Chung.Liew@freescale.com>

board/esd/common/flash.c

@@ -22,7 +22,9 @@
  */
 
 #include <common.h>
+#ifdef __PPC__
 #include <ppc4xx.h>
+#endif
 #include <asm/processor.h>
 
 flash_info_t	flash_info[CFG_MAX_FLASH_BANKS]; /* info for FLASH chips	*/