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.

Tested-by: Tanmay Inamdar <tinamdar@apm.com>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>