ar71xx: Add support for WZR-HP-G301NH

Add support for the Buffalo WZR-HP-G301NH. The only difference between it
and the WZR-HP-G00NH is that it has a RTL8366RB instead of a RTL8366S.
Since we don't do runtime detection of the switch, we need a separate
machine definition for it.

While we are at it, also rename the profile to reflect that it now is for
more than one device.

Signed-off-by: Jonas Gorski <jonas.gorski+openwrt@gmail.com>
SVN-Revision: 26601