net: cpsw: remove two unused global functions

The funtions, cpsw_ale_flush and cpsw_ale_set_ageout, have never been used
since they were first introduced.  This patch removes the dead code.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>