pci/layerscape: remove unnecessary pcie_layerscape.h

The patch uses the common function name ft_pci_setup to replace
ft_pcie_setup, then removes unnecessary pcie_layerscape.h because
all the functions have been declared in common.h.

Signed-off-by: Minghuan Lian <Minghuan.Lian@freescale.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: York Sun <yorksun@freescale.com>