Sys_lookup_dcookie arguments occupy 4 argument slots.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/scall32-o32.S

@@ -587,7 +587,7 @@ einval:	li	v0, -EINVAL
 	sys	sys_io_submit		3
 	sys	sys_io_cancel		3	/* 4245 */
 	sys	sys_exit_group		1
-	sys	sys_lookup_dcookie	3
+	sys	sys_lookup_dcookie	4
 	sys	sys_epoll_create	1
 	sys	sys_epoll_ctl		4
 	sys	sys_epoll_wait		3	/* 4250 */