PCI: imx6: Add PLL lock check for i.MX95 SoC

PCI: imx6: Add PLL lock check for i.MX95 SoC

PLL lock is required to ensure that the PLL clock is stable before enabling
the controller in i.MX95 SoC.

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/20250416081314.3929794-7-hongxing.zhu@nxp.com