mx31pdk: Allow booting a zImage kernel

Allow booting a zImage kernel.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
diff --git a/include/configs/mx31pdk.h b/include/configs/mx31pdk.h
index 49d440b..6ce97bc 100644
--- a/include/configs/mx31pdk.h
+++ b/include/configs/mx31pdk.h
@@ -99,6 +99,7 @@
 #define CONFIG_CMD_SPI
 #define CONFIG_CMD_DATE
 #define CONFIG_CMD_NAND
+#define CONFIG_CMD_BOOTZ
 
 /*
  * Disabled due to compilation errors in cmd_bootm.c (IMLS seems to require