perf: duplicate deletion of perf event

a malicious app can open a perf event with constraint_duplicate
bit set, disable the event, and close the fd.  On closing the fd,
the perf_release() modification causes the kernel to clean up
the event as if it still were enabled, leading to the event
being removed from a list twice.

CRs-Fixed: 977563
Change-Id: I5fbec3722407d2f3d0ff0d9f7097c5889e31fd62
Signed-off-by: Srinivasarao P <spathi@codeaurora.org>