perf/marvell_cn10k: Fix tad_pmu_event_init() to check pmu type first

Make sure to check the pmu type first and then check event->attr.disabled.
Doing so would avoid reading the disabled attribute of an event that is
not handled by TAD PMU.

Signed-off-by: Tanmay Jagdale <tanmay@marvell.com>
Link: https://lore.kernel.org/r/20220510102657.487539-1-tanmay@marvell.com
Signed-off-by: Will Deacon <will@kernel.org>