microblaze: Enable pselect6 syscall

Enable this syscall and cleanup comments.

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 b882ad5..38fc472 100644
--- a/arch/microblaze/kernel/syscall_table.S
+++ b/arch/microblaze/kernel/syscall_table.S
@@ -308,7 +308,7 @@
 	.long sys_readlinkat		/* 305 */
 	.long sys_fchmodat
 	.long sys_faccessat
-	.long sys_ni_syscall /* pselect6 */
+	.long sys_pselect6
 	.long sys_ppoll
 	.long sys_unshare		/* 310 */
 	.long sys_set_robust_list