mpc85xx: Add missing include in mpc85xx_sleep.c

This file needs the include file that provides the prototypes for
flush_dcache() and others.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/board/freescale/common/mpc85xx_sleep.c b/board/freescale/common/mpc85xx_sleep.c
index 770fa0d..d4ca278 100644
--- a/board/freescale/common/mpc85xx_sleep.c
+++ b/board/freescale/common/mpc85xx_sleep.c
@@ -4,6 +4,7 @@
  */
 
 #include <log.h>
+#include <asm/cache.h>
 #include <asm/global_data.h>
 #include <asm/immap_85xx.h>
 #include "sleep.h"