net: cxgb3: Remove stid deadcode

cxgb3_alloc_stid() and cxgb3_free_stid() have been unused since
commit 30e0f6cf ("RDMA/iw_cxgb3: Remove the iw_cxgb3 module
from kernel")

Remove them.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Link: https://patch.msgid.link/20241013012946.284721-1-linux@treblig.org


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