powerpc/pseries/dlpar: Eliminate use after free

dlpar_free_cc_nodes frees its argument, so dlpar_online_cpu should not be
called on the same value.  Skip over the call to dlpar_online_cpu by
jumping directly to out.

A simplified version of the semantic patch that finds this problem is as
follows: (http://coccinelle.lip6.fr/

)

// <smpl>
@@
expression E,E2;
@@

dlpar_free_cc_nodes(E)
...
(
  E = E2
|
* E
)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>