rockchip: backport pcie fix for rk3399

rockchip: backport pcie fix for rk3399

This patch resolves the LAN port not initializing on the
FriendlyElec NanoPI R4S, especially during warm reboots.

Upstream commit patch is based on:
https://github.com/torvalds/linux/commit/c3fe7071e196e25789ecf90dbc9e8491a98884d7

I've experienced the LAN port failing to initialize from a cold boot and
after a reboot. Other users have reported this issue on
https://forum.openwrt.org/t/nanopi-r4s-rk3399-is-a-great-new-openwrt-device/79143.
The NanoPI R4S has its LAN port connected to the RK3399 via PCIE. Since the
PCIE lanes don't initialize correctly after reboot, the LAN port
doesn't initialize.

Signed-off-by: Timothy Feierabend <tim.feierabend@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/20406
Signed-off-by: Nick Hainke <vincent@systemli.org>