MIPS: PCI: Byteswap not needed in little-endian mode

Rename function xlp_enable_pci_bswap() to xlp_config_pci_bswap(), which
is a better description for its functionality.  When compiled in
big-endian mode, xlp_config_pci_bswap() will configure the PCIe links
to byteswap.  In little-endian mode, no swap configuration is needed
for the PCIe controller, and the function is empty.

Signed-off-by: Jayachandran C <jchandra@broadcom.com>
Patchwork: http://patchwork.linux-mips.org/patch/4802/
Signed-off-by: John Crispin <blogic@openwrt.org>