PCI: dw-rockchip: Enable ASPM L0s capability for both RC and EP modes

L0s capability isn't enabled on all Rockchip SoCs by default, so enable it
in order to make ASPM L0s work on Rockchip platforms.

Testing the L0s for a long time revealed that the default N_FTS value of
210 in the hardware doesn't work stable and causes LTSSM to switch between
L0s and Recovery states. This leads to long exit latency and also causes
link down sometimes. So override the value to the max 255, which seems to
work fine under both PHYs used on Rockchip platforms.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
[mani: subject and description rewording]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://patch.msgid.link/1744850111-236269-2-git-send-email-shawn.lin@rock-chips.com