PCI: imx6: Propagate .host_init() errors to caller

Since dw_pcie_host_init() checks for errors from ops->host_init(),
check for errors when enabling power regulators and clocks and return them.

[bhelgaas: commit log]
Link: https://lore.kernel.org/r/1657783869-19194-8-git-send-email-hongxing.zhu@nxp.com


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