cifs: add and use CIFSSMBUnixSetFileInfo for setattr calls

When there's an open filehandle, SET_FILE_INFO is apparently preferred
over SET_PATH_INFO. Add a new variant that sets a FILE_UNIX_INFO_BASIC
infolevel via SET_FILE_INFO and switch cifs_setattr_unix to use the
new call when there's an open filehandle available.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>