Add in the imx-atf repo to the checkouts.

Change-Id: Iad3cdb0585b79dd1e3b8c51e4f788c49c0e0d653
diff --git a/default.xml b/default.xml
index c71784c..a070338 100644
--- a/default.xml
+++ b/default.xml
@@ -18,6 +18,8 @@
       groups="notdefault,imx"/>
     <project name="imx-firmware" path="imx-firmware"
       groups="notdefault,imx"/>
+    <project name="imx-atf" path="imx-atf"
+      groups="notdefault,imx"/>
 
     <project name="uboot-imx" path="uboot-imx"
       groups="notdefault,imx"/>