PCI: imx6: Move PHY management functions together

Collect imx6_pcie_init_phy(), imx7d_pcie_wait_for_phy_pll_lock(), and
imx6_setup_phy_mpll() earlier with other PHY-related code.  No functional
change intended.

Link: https://lore.kernel.org/r/1657783869-19194-3-git-send-email-hongxing.zhu@nxp.com


Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Richard Zhu <hongxing.zhu@nxp.com>