PCI: imx6: Skip waiting for L2/L3 Ready on i.MX6SX

On i.MX6SX, the LTSSM registers become inaccessible after the
PME_Turn_Off message is sent to the link. So there is no way to verify
whether the link has entered L2/L3 Ready state or not.

Hence, set IMX_PCIE_FLAG_SKIP_L23_READY flag for i.MX6SX SoC to skip the
L2/L3 Ready state polling and let the DWC core wait for 10ms after sending
the PME_Turn_Off message as per the PCIe spec r6.0, sec 5.3.3.2.1.

Fixes: a528d1a ("PCI: imx6: Use DWC common suspend resume method")
Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
[mani: commit log]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260228080925.1558395-1-hongxing.zhu@nxp.com

Author: Richard Zhu

drivers/pci/controller/dwc/pci-imx6.c

@@ -1876,6 +1876,7 @@ static const struct imx_pcie_drvdata drvdata[] = {
 		.variant = IMX6SX,
 		.flags = IMX_PCIE_FLAG_IMX_PHY |
 			 IMX_PCIE_FLAG_SPEED_CHANGE_WORKAROUND |
+			 IMX_PCIE_FLAG_SKIP_L23_READY |
 			 IMX_PCIE_FLAG_SUPPORTS_SUSPEND,
 		.gpr = "fsl,imx6q-iomuxc-gpr",
 		.ltssm_off = IOMUXC_GPR12,