alpha: remove unneeded semicolon in osf_sys.c

Fix the following coccicheck warning:

arch/alpha/kernel/osf_sys.c:680:2-3: Unneeded semicolon
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Matt Turner <mattst88@gmail.com>

arch/alpha/kernel/osf_sys.c

@@ -677,7 +677,7 @@ SYSCALL_DEFINE2(osf_proplist_syscall, enum pl_code, code,
 	default:
 		error = -EOPNOTSUPP;
 		break;
-	};
+	}
 	return error;
 }