fpga/dfl-pci.c: Replace deprecated PCI functions

fpga/dfl-pci.c: Replace deprecated PCI functions

pcim_iomap_regions() and pcim_iomap_table() have been deprecated by the
PCI subsystem in commit e354bb84a4c1 ("PCI: Deprecate
pcim_iomap_table(), pcim_iomap_regions_request_all()").

Port dfl-pci.c to the successor, pcim_iomap_region().

Consistently, replace pcim_iounmap_regions() with pcim_iounmap_region().

Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Philipp Stanner <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Acked-by: Xu Yilun <[email protected]>