cifs: eliminate cifs_init_private

...it does the same thing as cifs_fill_fileinfo, but doesn't handle the
flist ordering correctly. Also rename cifs_fill_fileinfo to a more
descriptive name and have it take an open flags arg instead of just a
write_only flag. That makes the logic in the callers a little simpler.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>