powerpc/spufs: Fix build warning when CONFIG_PROC_FS=n

arch/powerpc/platforms/cell/spufs/sched.c:1055:12: warning: ‘show_spu_loadavg’ defined but not used [-Wunused-function]
 static int show_spu_loadavg(struct seq_file *s, void *private)
            ^~~~~~~~~~~~~~~~

Move it into #ifdef block to fix this, also remove unneeded semicolon.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220308100928.23540-1-yuehaibing@huawei.com

arch/powerpc/platforms/cell/spufs/sched.c

@@ -1052,6 +1052,7 @@ void spuctx_switch_state(struct spu_context *ctx,
 	}
 }
 
+#ifdef CONFIG_PROC_FS
 static int show_spu_loadavg(struct seq_file *s, void *private)
 {
 	int a, b, c;
@@ -1073,7 +1074,8 @@ static int show_spu_loadavg(struct seq_file *s, void *private)
 		atomic_read(&nr_spu_contexts),
 		idr_get_cursor(&task_active_pid_ns(current)->idr) - 1);
 	return 0;
-};
+}
+#endif
 
 int __init spu_sched_init(void)
 {