Remove empty devtrees

At the moment the in-tree devtrees are used.  Remove these to
minimize confusion.

Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/meta-firestone/recipes-kernel/linux/linux-obmc/firestone.dts b/meta-firestone/recipes-kernel/linux/linux-obmc/firestone.dts
deleted file mode 100644
index 3b5e0f1..0000000
--- a/meta-firestone/recipes-kernel/linux/linux-obmc/firestone.dts
+++ /dev/null
@@ -1 +0,0 @@
-# use in-tree devtree
diff --git a/meta-garrison/recipes-kernel/linux/linux-obmc/garrison.dts b/meta-garrison/recipes-kernel/linux/linux-obmc/garrison.dts
deleted file mode 100644
index 3b5e0f1..0000000
--- a/meta-garrison/recipes-kernel/linux/linux-obmc/garrison.dts
+++ /dev/null
@@ -1 +0,0 @@
-# use in-tree devtree
diff --git a/meta-palmetto/recipes-kernel/linux/linux-obmc/palmetto.dts b/meta-palmetto/recipes-kernel/linux/linux-obmc/palmetto.dts
deleted file mode 100644
index 3b5e0f1..0000000
--- a/meta-palmetto/recipes-kernel/linux/linux-obmc/palmetto.dts
+++ /dev/null
@@ -1 +0,0 @@
-# use in-tree devtree