powerpc/powernv: Switch from __FUNCTION__ to __func__

__FUNCTION__ exists only for backwards compatibility reasons with old
gcc versions. Replace it with __func__.
Signed-off-by: Dwaipayan Ray <dwaipayanray1@gmail.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210711084837.95577-1-dwaipayanray1@gmail.com

arch/powerpc/platforms/powernv/opal-imc.c

@@ -211,7 +211,7 @@ static void disable_core_pmu_counters(void)
 					    get_hard_smp_processor_id(cpu));
 		if (rc)
 			pr_err("%s: Failed to stop Core (cpu = %d)\n",
-				__FUNCTION__, cpu);
+				__func__, cpu);
 	}
 	cpus_read_unlock();
 }