This patch makes the calls to futex_get_key_refs() and futex_drop_key_refs()
explicitly symmetric by only "putting" keys we successfully "got". Also
cleanup a couple return points that didn't "put" after a successful "get".
Build and boot tested on an x86_64 system.
Signed-off-by: Darren Hart <dvhltc@us.ibm.com> Cc: <stable@kernel.org> Signed-off-by: Ingo Molnar <mingo@elte.hu>