PCI: layerscape: Move generic init functions earlier in file

We will use the generic ls_pcie_link_up() and ls_pcie_host_init() from
device-specific routines.  Move the generic functions earlier in the file
so we won't need forward declarations.  This is strictly a code move with
no functional change intended.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Roy Zang <tie-fei.zang@freescale.com>