imx: ventana: remove SPL_EXT_SUPPORT

Remove SPL_EXT_SUPPORT to resolve build issue. It may be useful to bring
it back in the future after comparing its merits to storing the args/kernel
in fixed raw locations.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
diff --git a/include/configs/gw_ventana.h b/include/configs/gw_ventana.h
index c8d3cb8..874bb04 100644
--- a/include/configs/gw_ventana.h
+++ b/include/configs/gw_ventana.h
@@ -32,6 +32,7 @@
 
 #include "imx6_spl.h"                  /* common IMX6 SPL configuration */
 #include "mx6_common.h"
+#undef CONFIG_SPL_EXT_SUPPORT
 
 #define CONFIG_MACH_TYPE	4520   /* Gateworks Ventana Platform */