net: fddi: skfp: cfm: Remove set but unused variable 'oldstate'

While we're at it, remove some code which has never been invoked.

Keep the comment though, as it seems potentially half useful.

Fixes the following W=1 kernel build warning(s):

 drivers/net/fddi/skfp/cfm.c: In function ‘cfm’:
 drivers/net/fddi/skfp/cfm.c:211:6: warning: variable ‘oldstate’ set but not used [-Wunused-but-set-variable]

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: netdev@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>