smb3: cleanup some recent endian errors spotted by updated sparse

Now that sparse has been fixed, it spotted a couple recent minor
endian errors (and removed one additional sparse warning).

Thanks to Luc Van Oostenryck for his help fixing sparse.

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>