[MIPS] Add support for kexec

A tiny userland application loading the kernel and invoking kexec_load for 
mips is available here:

http://chac.le-poulpe.net/~nico/kexec/kexec-2006-10-18.tar.gz

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kernel/scall32-o32.S b/arch/mips/kernel/scall32-o32.S
index a95f37d..7c0b393 100644
--- a/arch/mips/kernel/scall32-o32.S
+++ b/arch/mips/kernel/scall32-o32.S
@@ -653,7 +653,7 @@
 	sys	sys_move_pages		6
 	sys	sys_set_robust_list	2
 	sys	sys_get_robust_list	3	/* 4310 */
-	sys	sys_ni_syscall		0
+	sys	sys_kexec_load		4
 	sys	sys_getcpu		3
 	sys	sys_epoll_pwait		6
 	.endm