mx53evk: add boot_mode support

This allows a watchdog reset to start the ROM's
usb/serial downloader, or boot from an sdcard.

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
diff --git a/include/configs/mx53evk.h b/include/configs/mx53evk.h
index 0a79833..b46855f 100644
--- a/include/configs/mx53evk.h
+++ b/include/configs/mx53evk.h
@@ -88,6 +88,9 @@
 #define CONFIG_CMD_NET
 #define CONFIG_CMD_DATE
 
+/* Miscellaneous commands */
+#define CONFIG_CMD_BMODE
+
 /* allow to overwrite serial and ethaddr */
 #define CONFIG_ENV_OVERWRITE
 #define CONFIG_CONS_INDEX		1