ionic: remove the unused nb_work

ionic: remove the unused nb_work

Remove the empty and unused nb_work and associated
ionic_lif_notify_work() function.

v2: separated from previous net patch

Link: https://lore.kernel.org/netdev/20241210174828.69525-2-shannon.nelson@amd.com/
Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Link: https://patch.msgid.link/20241212212042.9348-1-shannon.nelson@amd.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>