drivers: perf: arm_pmu: Drop 'pmu_lock' element from 'struct pmu_hw_events'

As 'pmu_lock' element is not being used in any ARM PMU implementation, just
drop this from 'struct pmu_hw_events'.

Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20231115092805.737822-3-anshuman.khandual@arm.com


Signed-off-by: Will Deacon <will@kernel.org>