microblaze: Wire-up preadv/pwritev in syscall table

Enable these two syscalls.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/arch/microblaze/kernel/syscall_table.S b/arch/microblaze/kernel/syscall_table.S
index 38fc472..c09d741 100644
--- a/arch/microblaze/kernel/syscall_table.S
+++ b/arch/microblaze/kernel/syscall_table.S
@@ -363,8 +363,8 @@
 	.long sys_sendmsg		/* 360 */
 	.long sys_recvmsg
 	.long sys_accept4
-	.long sys_ni_syscall
-	.long sys_ni_syscall
+	.long sys_preadv
+	.long sys_pwritev
 	.long sys_rt_tgsigqueueinfo	/* 365 */
 	.long sys_perf_event_open
 	.long sys_recvmmsg