CRIS: Define io_remap_pfn_range as remap_pfn_range

CRIS don't need any special mapping for io, but didn't define this,
meaning that all uses of io_remap_pfn_range lead to compile errors.

This fixes a compile error introduced in CRIS when drivers/mtd/mtdchar.c
mmap handling was changed in commit dd02b67d5e9e7896891fa27eb5db65f55a290998

Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>