Revert "ARM: 7556/1: perf: fix updated event period in response to PERF_EVENT_IOC_PERIOD"

This reverts commit 3581fe0e

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Fixes to the handling of PERF_EVENT_IOC_PERIOD in the core code mean
we no longer have to play this horrible game.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1385560479-11014-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>