arm64: perf_event: Remove wrongfully used inline

The functions armv8pmu_read_counter() and armv8pmu_write_counter()
are `static inline` while they are only referenced when assigned
to a function pointer field in a `struct arm_pmu` instance.

The inline keyword is thus counter intuitive and shouldn't be used.

Acked-by: Mark Rutland <[e-mail]>
Signed-off-by: Raphael Gault <[e-mail]>
Signed-off-by: Will Deacon <[e-mail]>

arch/arm64/kernel/perf_event.c

···
 	return val;
 }
 
-static inline u64 armv8pmu_read_counter(struct perf_event *event)
+static u64 armv8pmu_read_counter(struct perf_event *event)
 {
 	struct arm_pmu *cpu_pmu = to_arm_pmu(event->pmu);
 	struct hw_perf_event *hwc = &event->hw;
···
 	}
 }
 
-static inline void armv8pmu_write_counter(struct perf_event *event, u64 value)
+static void armv8pmu_write_counter(struct perf_event *event, u64 value)
 {
 	struct arm_pmu *cpu_pmu = to_arm_pmu(event->pmu);
 	struct hw_perf_event *hwc = &event->hw;