PCI: imx6: Add workaround for errata ERR051586

PCI: imx6: Add workaround for errata ERR051586

ERR051586: Compliance with 8GT/s Receiver Impedance ECN.

The default value of GEN3_RELATED_OFF[GEN3_ZRXDC_NONCOMPL] is 1 which
makes receiver non-compliant with the ZRX-DC parameter for 2.5 GT/s when
operating at 8 GT/s or higher. It causes unnecessary timeout in L1.

So the workaround is to set GEN3_RELATED_OFF[GEN3_ZRXDC_NONCOMPL] to 0.
Add this workaround in the dw_pcie_host_ops::post_init() callback for
i.MX95 platforms.

Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
[mani: subject and description rewording]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://patch.msgid.link/20250416081314.3929794-6-hongxing.zhu@nxp.com