PCI: bt1: Set 64-bit DMA mask

The DW PCIe Root Port IP core is synthesized with the 64-bit AXI address
bus.  Since the device is also equipped with the eDMA engine, explicitly
set the device DMA mask so DMA engine clients can allocate data buffers
anywhere in the 64-bit memory space.

Link: https://lore.kernel.org/r/20230113171409.30470-27-Sergey.Semin@baikalelectronics.ru


Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>