smb: client: compress: fix counting in LZ77 match finding

smb: client: compress: fix counting in LZ77 match finding

- lz77_match_len() increments @cur before checking for equality,
  leading to off-by-one match len in some cases.

  Fix by moving pointers increment to inside the loop.
  Also rename @wnd arg to @match (more accurate name).
- both lz77_match_len() and lz77_compress() checked for
  "buf + step < end" when the correct is "<=" for such cases.

Signed-off-by: Enzo Matsumiya <ematsumiya@suse.de>
Signed-off-by: Steve French <stfrench@microsoft.com>