perf: arm_v7_pmu: Don't disable counter in (armv7|krait_|scorpion_)pmu_enable_event()

Currently (armv7|krait_|scorpion_)pmu_enable_event() start by disabling
the event counter it has been asked to enable. This should not be
necessary as the counter (and the PMU as a whole) should not be active
when *_enable_event() is called.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Tested-by: James Clark <james.clark@linaro.org>
Link: https://lore.kernel.org/r/20250218-arm-brbe-v19-v20-5-4e9922fc2e8e@kernel.org


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