perf: dsu: Use signed field for dsu_pmu->num_counters

We set dsu_pmu->num_counters to -1, when the DSU is allocated
but not initialised when none of the CPUs are active in the DSU.
However, we use an unsigned field for num_counters. Switch this
to a signed field.

Fixes: 7520fa9 ("perf: ARM DynamIQ Shared Unit PMU support")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

drivers/perf/arm_dsu_pmu.c

@@ -120,7 +120,7 @@ struct dsu_pmu {
 	cpumask_t			associated_cpus;
 	cpumask_t			active_cpu;
 	struct hlist_node		cpuhp_node;
-	u8				num_counters;
+	s8				num_counters;
 	int				irq;
 	DECLARE_BITMAP(cpmceid_bitmap, DSU_PMU_MAX_COMMON_EVENTS);
 };