pci: pcie_dw_rockchip: Speed up link probe

Use a similar pattern and delay values as the linux mainline driver to
speed up failing when nothing is connected.

Reduce fail speed from around 5+ seconds down to around one second on a
Radxa ROCK 3 Model A, where pcie2x1 is probed before pcie3x2 M2 slot.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>