arm64: pmu: Hoist pmu platform device name

Move the PMU name into a common header file so it may
be referenced by other users.

Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index 92dbe88..a9310a6 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -1111,7 +1111,7 @@
 
 static struct platform_driver armv8_pmu_driver = {
 	.driver		= {
-		.name	= "armv8-pmu",
+		.name	= ARMV8_PMU_PDEV_NAME,
 		.of_match_table = armv8_pmu_of_device_ids,
 	},
 	.probe		= armv8_pmu_device_probe,