MIPS: compat: Return same error ENOSYS as native for invalid operation.

The pains for multiplexed syscalls.

Noticed by Al Viro <viro@zeniv.linux.org.uk>.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/kernel/linux32.c

@@ -171,7 +171,7 @@ SYSCALL_DEFINE6(32_ipc, u32, call, long, first, long, second, long, third,
 		err = compat_sys_shmctl(first, second, compat_ptr(ptr));
 		break;
 	default:
-		err = -EINVAL;
+		err = -ENOSYS;
 		break;
 	}