ionic: remove old work task types

With the move of mac filter handling to outside of the
ndo_rx_mode context using the IONIC_DW_TYPE_RX_MODE,
we no longer are using IONIC_DW_TYPE_RX_ADDR_ADD and
IONIC_DW_TYPE_RX_ADDR_DEL and they can be removed.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>