ramips: create new dtsi for Arcadyan routers

ramips: create new dtsi for Arcadyan routers

This commit moves common properties for the boards below to a new dtsi:
Beeline Smartbox Flash (Arcadyan WG443223)
MTS WG430223 (Arcadyan WG430223)

The boards are almost the same. Here is the differences:
+------+----------+----------+
|      | WG430223 | WG443223 |
+------+----------+----------+
| RAM  | 128      | 256      |
+------+----------+----------+
| USB  | -        | 1x3.0    |
+------+----------+----------+
| LEDS | RG       | RGB      |
+------+----------+----------+

Signed-off-by: Mikhail Zhilkin <csharper2005@gmail.com>