asm-generic/io.h: Fix ioport_map() for !CONFIG_GENERIC_IOMAP
The !CONFIG_GENERIC_IOMAP version of ioport_map() is wrong. It returns a
mapped, i.e., virtual, address that can start from zero and completely
ignores the PCI_IOBASE and IO_SPACE_LIMIT that most architectures that use
!CONFIG_GENERIC_MAP define.