We don't unlock the mutex if we fail to allocate the parent names
array. Unlock it and return an error in this case as well.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Cc: Sergej Sawazki <ce3a@gmx.de>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>