The seq_file_operations' dev_mc_seq_xxx callbacks do the same thing as
the dev_seq_xxx ones do, but skip the SEQ_START_TOKEN.

So use the existing exported dev_seq_xxx calls and handle the
SEQ_START_TOKEN in the dev_mc_seq_show().
Signed-off-by: NPavel Emelyanov <xemul@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>