cxgb3/l2t: Remove unused t3_l2t_send_event

The last use of t3_l2t_send_event() was removed in 2019 by
commit 30e0f6cf ("RDMA/iw_cxgb3: Remove the iw_cxgb3 module from
kernel")

Remove it.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Link: https://patch.msgid.link/20250609152330.24027-1-linux@treblig.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>