net: mvpp2: cls: Check RSS table index validity when creating a context

Make sure we don't use an out-of-bound index for the per-port RSS
context array.

As of today, the global context creation in mvpp22_rss_context_create
will prevent us from reaching this case, but we should still make sure
we are using a sane value anyway.
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/mvpp2/mvpp2_cls.c

@@ -1466,6 +1466,9 @@ int mvpp22_port_rss_ctx_create(struct mvpp2_port *port, u32 *port_ctx)
 			break;
 	}
 
+	if (i == MVPP22_N_RSS_TABLES)
+		return -EINVAL;
+
 	port->rss_ctx[i] = rss_ctx;
 	*port_ctx = i;