Windows: always open dscp in smb_ReceiveNTTranCreate

Windows: always open dscp in smb_ReceiveNTTranCreate

There were two code paths in smb_ReceiveNTTranCreate that included
asserts in case the directory cm_scache_t object had not been
evaluated.  RT129299 contains a report that at least one of
them had been tripped in production.  There is no reason to avoid
evaluating the directory scp.  It must exist in the cache and
obtaining a reference in all cases simplifies the logic of this
overly complex function.

FIXES 129299

Change-Id: I7b32c81f11c3fef53f8a21a44f3594d5cd9e1552
Reviewed-on: http://gerrit.openafs.org/4967
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jeffrey Altman <jaltman@openafs.org>