This board support code can be used for TP-LINK WR703 too.

TP-LINK WR703 is very similar to TP-LINK MR3020, there are
some non-essential differences:

  * WR703 is smaller and cheaper;
  * WR703 has only one led, but MR3020 has five leds;
  * MR3020 uses mini-USB connector, WR703 uses micro-USB connector.

See https://forum.openwrt.org/viewtopic.php?id=45159 for details.

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>