microblaze: Enable ppoll syscall

Signed-off-by: Michal Simek <monstr@monstr.eu>

arch/microblaze/kernel/syscall_table.S

@@ -313,7 +313,7 @@ ENTRY(sys_call_table)
 	.long sys_fchmodat
 	.long sys_faccessat
 	.long sys_ni_syscall /* pselect6 */
-	.long sys_ni_syscall /* sys_ppoll */
+	.long sys_ppoll
 	.long sys_unshare		/* 310 */
 	.long sys_set_robust_list
 	.long sys_get_robust_list