There's currently an off-by-one bug in fdt_subnode_offset_namelen()
which causes it to keep searching after it's finished the subnodes of
the given parent, and into the subnodes of siblings of the original
node which come after it in the tree.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>