Basic support for Firestone and Garrison systems

Firestone and Garrison are IBM branded OpenPOWER systems.
diff --git a/meta-firestone/recipes-kernel/linux/linux-obmc/firestone.dts b/meta-firestone/recipes-kernel/linux/linux-obmc/firestone.dts
new file mode 100644
index 0000000..3b5e0f1
--- /dev/null
+++ b/meta-firestone/recipes-kernel/linux/linux-obmc/firestone.dts
@@ -0,0 +1 @@
+# use in-tree devtree