drivers: perf: Register/unregister on perf

Before registering perf structures make sure
it has not yet been registered before.
Conversely, if deregistering perf, make sure
that it was registered in the first place.

Signed-off-by: Conner Huff <chuff@codeaurora.org>
Change-Id: I00b89f45780161615b25faebfa70e79dde530c2f