[DCCP]: fix memory leak and clean up style - dccp_feat_empty_confirm()

There's a memory leak in net/dccp/feat.c::dccp_feat_empty_confirm().  If we
hit the 'default:' case of the 'switch' statement, then we return without
freeing 'opt', thus leaking 'struct dccp_opt_pend' bytes.

The leak is fixed easily enough by adding a kfree(opt); before the return
statement.

The patch also changes the layout of the 'switch' to be more in line with
CodingStyle.

Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>