net/mwan3: set default mask to 0x3F00

The IPsec ip route table has the default number 220.
If mwan3 has more then 7 bits set (124 interfaces) then if mwan3 down is
executed the table is also cleared. To solve this set default max 7
bits in the mmx_mask for mwan3.

Signed-off-by: Florian Eckert <fe@dev.tdt.de>

net/mwan3/files/lib/mwan3/mwan3.sh

@@ -69,7 +69,7 @@ mwan3_init()
 		MWAN3_INTERFACE_MAX=$(uci_get_state mwan3 globals iface_max)
 	else
 		config_load mwan3
-		config_get MMX_MASK globals mmx_mask '0xff00'
+		config_get MMX_MASK globals mmx_mask '0x3F00'
 		echo "$MMX_MASK" > "${MWAN3_STATUS_DIR}/mmx_mask"
 		$LOG notice "Using firewall mask ${MMX_MASK}"