NLS: improve UTF8 -> UTF16 string conversion routine

The utf8s_to_utf16s conversion routine needs to be improved.  Unlike
its utf16s_to_utf8s sibling, it doesn't accept arguments specifying
the maximum length of the output buffer or the endianness of its
16-bit output.

This patch (as1501) adds the two missing arguments, and adjusts the
only two places in the kernel where the function is called.  A
follow-on patch will add a third caller that does utilize the new
capabilities.

The two conversion routines are still annoyingly inconsistent in the
way they handle invalid byte combinations.  But that's a subject for a
different patch.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
static int vfat_find_form(struct inode *dir, unsigned char *name)
{
	struct fat_slot_info sinfo;
	int err = fat_scan(dir, name, &sinfo);
	if (err)
		return -ENOENT;
	brelse(sinfo.bh);
	return 0;
}

static int vfat_find_form(struct inode *dir, unsigned char *name)
{
	struct fat_slot_info sinfo;
	int err = fat_scan(dir, name, &sinfo);
	if (err)
		return -ENOENT;
	brelse(sinfo.bh);
	return 0;
}
