Previously callers of dw_pcie_disable_atu() supplied enum
dw_pcie_region_type (DW_PCIE_REGION_INBOUND, DW_PCIE_REGION_OUTBOUND),
which dw_pcie_disable_atu() converted to the PCIE_ATU_REGION_DIR_IB or
PCIE_ATU_REGION_DIR_OB values needed to program the ATU registers.

Simplify the code by dropping the dw_pcie_region_type enum and passing
PCIE_ATU_REGION_DIR_IB or PCIE_ATU_REGION_DIR_OB directly.

Reorder dw_pcie_disable_atu() arguments to (dir, index) since "index"
indicates an ATU window in the regions of the corresponding direction.

[bhelgaas: commit log]
Link: https://lore.kernel.org/r/20220624143947.8991-11-Sergey.Semin@baikalelectronics.ruSigned-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>