MIPS: SEAD3: Probe ethernet controller using DT

MIPS: SEAD3: Probe ethernet controller using DT

Probe the smsc911x ethernet controller using device tree rather than
platform code, reducing the amount of the latter.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14050/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>