csky: PCI: Define ARCH_GENERIC_PCI_MMAP_RESOURCE

csky: PCI: Define ARCH_GENERIC_PCI_MMAP_RESOURCE

This looks to be something that was accidentally left out on the csky port.
Define ARCH_GENERIC_PCI_MMAP_RESOURCE to keep it inline with other ports.
Adding ARCH_GENERIC_PCI_MMAP_RESOURCE enables the definition of modern
pci_mmap_resource_range() functions which is generally what new ports
should be using.

Link: https://lore.kernel.org/r/20220722214944.831438-4-shorne@gmail.com
Signed-off-by: Stafford Horne <shorne@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Guo Ren <guoren@kernel.org>