MIPS: Octeon: Fix DT pruning bug with pip ports

MIPS: Octeon: Fix DT pruning bug with pip ports

During the pruning of the device tree octeon_fdt_pip_iface() is called
for each PIP interface and every port up to the port count is removed
from the device tree. However, the count was set to the return value of
cvmx_helper_interface_enumerate() which doesn't actually return the
count but just returns zero on success. This effectively removed *all*
ports from the tree.

Use cvmx_helper_ports_on_interface() instead to fix this. This
successfully restores the 3 ports of my ERLite-3 and fixes the "kernel
assigns random MAC addresses" issue.

Signed-off-by: Faidon Liambotis <paravoid@debian.org>
Tested-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Acked-by: David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5587/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>