vm: convert mtdchar mmap to vm_iomap_memory() helper

	struct mtd_file_info *mfi = file->private_data;

	struct mtd_info *mtd = mfi->mtd;

	struct map_info *map = mtd->priv;

	resource_size_t start, off;

	unsigned long len, vma_len;

        /* This is broken because it assumes the MTD device is map-based

	   and that mtd->priv is a valid struct map_info.  It should be

	   replaced with something that uses the mtd_get_unmapped_area()

	   operation properly. */

	if (0 /*mtd->type == MTD_RAM || mtd->type == MTD_ROM*/) {

		off = get_vm_offset(vma);

		start = map->phys;

		len = PAGE_ALIGN((start & ~PAGE_MASK) + map->size);

		start &= PAGE_MASK;

		vma_len = get_vm_size(vma);

		/* Overflow in off+len? */

		if (vma_len + off < off)

			return -EINVAL;

		/* Does it fit in the mapping? */

		if (vma_len + off > len)

			return -EINVAL;

		off += start;

		/* Did that overflow? */

		if (off < start)

			return -EINVAL;

		if (set_vm_offset(vma, off) < 0)

			return -EINVAL;

		vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;

#ifdef pgprot_noncached

		if (file->f_flags & O_DSYNC || off >= __pa(high_memory))

		if (file->f_flags & O_DSYNC || map->phys >= __pa(high_memory))

			vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

#endif

		if (io_remap_pfn_range(vma, vma->vm_start, off >> PAGE_SHIFT,

				       vma->vm_end - vma->vm_start,

				       vma->vm_page_prot))

			return -EAGAIN;

		return 0;

		return vm_iomap_memory(vma, map->phys, map->size);

	}

	return -ENOSYS;

#else