octeon: ubnt-edgerouter: Disable PCIe

octeon: ubnt-edgerouter: Disable PCIe

Some devices lock up on PCIe initialization:

[   64.309697] PCIe: Port 0 in endpoint mode, skipping.
[   64.320496] PCIe: Initializing port 1
[   64.325257] PCIe: BIST FAILED for port 1 (0xffffffffffffffff)
(system hangs here)

Given the ER contains no PCIe peripherals, has no way to attach any
and the stock kernel doesn't have PCIe support either, just disable it.

(cherry picked from commit 308630aea6da1b5618d169d6ebf208aaa249ef72)
Signed-off-by: Jakob Haufe <sur5r@sur5r.net>
Link: https://github.com/openwrt/openwrt/pull/16223
Signed-off-by: Robert Marko <robimarko@gmail.com>