PCI: dwc: designware: Make dw_pcie_prog_*_atu_unroll() static

Helper functions dw_pcie_prog_*_atu_unroll() don't need to be in global
scope, so make them static.

Cleans up sparse warnings:
  - symbol 'dw_pcie_prog_outbound_atu_unroll' was not declared. Should it be static?
  - symbol 'dw_pcie_prog_inbound_atu_unroll' was not declared. Should it be static?

Signed-off-by: Carlos Palminha <palminha@synopsys.com>
[bhelgaas: rewrap to fit in 80 columns]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Joao Pinto <jpinto@synopsys.com>
Acked-by: Jingoo Han <jingoohan1@gmail.com>