microblaze: Enable accept4 syscall

We had wrong name in unistd.h + I wire up this syscall
in syscall table.

Signed-off-by: Michal Simek <monstr@monstr.eu>
diff --git a/arch/microblaze/kernel/syscall_table.S b/arch/microblaze/kernel/syscall_table.S
index 4088be7..03376dc 100644
--- a/arch/microblaze/kernel/syscall_table.S
+++ b/arch/microblaze/kernel/syscall_table.S
@@ -366,7 +366,7 @@
 	.long sys_shutdown
 	.long sys_sendmsg		/* 360 */
 	.long sys_recvmsg
-	.long sys_ni_syscall
+	.long sys_accept4
 	.long sys_ni_syscall
 	.long sys_ni_syscall
 	.long sys_rt_tgsigqueueinfo	/* 365 */