MIPS: configs: Add Onion Omega2+ defconfig

Create a defconfig for the Omega2+ that reaches userspace and
allows use of the USB port.

Signed-off-by: Harvey Hunt <harvey.hunt@imgtec.com>
Cc: robh+dt@kernel.org
Cc: mark.rutland@arm.com
Cc: john@phrozen.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17138/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>