MIPS: octeon: use of_platform_populate to probe devices

of_platform_bus_probe is deprecated in favor of of_platform_populate.
of_platform_populate is stricter requiring compatible properties for
matching rather than name or type. Octeon uses compatible strings for
matching, so convert it to of_platform_populate.

Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@linux-mips.org
Signed-off-by: Rob Herring <robh@kernel.org>
Patchwork: https://patchwork.linux-mips.org/patch/19588/
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-kernel@vger.kernel.org