Currently the 32-bit arm PMU drivers use the pmu_hw_events::lock spinlock in
their arm_pmu::{start,stop,enable,disable}() callbacks to protect hardware
state and event data.

This locking is not necessary as the perf core code already provides mutual
exclusion, disabling interrupts to serialize against the IRQ handler, and
using perf_event_context::lock to protect against concurrent modifications of
events cross-cpu.

The locking was removed from the arm64 (now PMUv3) PMU driver in commit:

2a0e2a02 ("arm64: perf: Remove PMU locking")

... and the same reasoning applies to all the 32-bit PMU drivers.

Remove the locking from the 32-bit PMU drivers.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: linux-perf-users@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20231115092805.737822-2-anshuman.khandual@arm.comSigned-off-by: Will Deacon <will@kernel.org>