powerpc: Add del_node() for early boot code to prune inapplicable devices.

Some platforms have variants that can share most of a flat device tree but need
a few devices selectively pruned at boot time.  This adds del_node() to ops.h
to allow access to the existing fdt_del_node().

Signed-off-by: Mike Ditto <mditto@consentry.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/boot/libfdt-wrapper.c b/arch/powerpc/boot/libfdt-wrapper.c
index 1daa73f..9276327 100644
--- a/arch/powerpc/boot/libfdt-wrapper.c
+++ b/arch/powerpc/boot/libfdt-wrapper.c
@@ -105,6 +105,11 @@
 	return check_err(rc);
 }
 
+static int fdt_wrapper_del_node(const void *devp)
+{
+	return fdt_del_node(fdt, devp_offset(devp));
+}
+
 static void *fdt_wrapper_get_parent(const void *devp)
 {
 	return offset_devp(fdt_parent_offset(fdt, devp_offset(devp)));
@@ -174,6 +179,7 @@
 	dt_ops.create_node = fdt_wrapper_create_node;
 	dt_ops.find_node_by_prop_value = fdt_wrapper_find_node_by_prop_value;
 	dt_ops.find_node_by_compatible = fdt_wrapper_find_node_by_compatible;
+	dt_ops.del_node = fdt_wrapper_del_node;
 	dt_ops.get_path = fdt_wrapper_get_path;
 	dt_ops.finalize = fdt_wrapper_finalize;