PCI: imx6: Add IMX8MQ_EP third 64-bit BAR in epc_features

IMX8MQ_EP has three 64-bit BAR0/2/4 capable and programmable BARs. For
IMX8MQ_EP, use imx8q_pcie_epc_features (64-bit BARs 0, 2, 4) instead
of imx8m_pcie_epc_features (64-bit BARs 0, 2).

Fixes: 75c2f26d ("PCI: imx6: Add i.MX PCIe EP mode support")
Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
[bhelgaas: add details in subject]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20250708091003.2582846-2-hongxing.zhu@nxp.com