Handle big endianness in NTLM (ntlmv2) authentication

This is RH bug 970891
Uppercasing of username during calculation of ntlmv2 hash fails
because UniStrupr function does not handle big endian wchars.

Also fix a comment in the same code to reflect its correct usage.

[To make it easier for stable (rather than require 2nd patch) fixed
this patch of Shirish's to remove endian warning generated
by sparse -- steve f.]

Reported-by: steve <sanpatr1@in.ibm.com>
Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Cc: <stable@kernel.org>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>