[POWERPC] Check for the root node in of_detach_node()

It's not sensible to call of_detach_node() on the root node,
but we should check for it just to be safe.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
1 file changed