image: Add support for Plan 9

Signed-off-by: Steven Stallion <sstallion@gmail.com>
Cc: Tom Rini <trini@ti.com>
Reviewed-by: Tom Rini <trini@ti.com>
diff --git a/include/config_defaults.h b/include/config_defaults.h
index d023c63..567b46c 100644
--- a/include/config_defaults.h
+++ b/include/config_defaults.h
@@ -12,6 +12,7 @@
 /* Support bootm-ing different OSes */
 #define CONFIG_BOOTM_LINUX 1
 #define CONFIG_BOOTM_NETBSD 1
+#define CONFIG_BOOTM_PLAN9 1
 #define CONFIG_BOOTM_RTEMS 1
 
 #define CONFIG_GZIP 1