scsi: iscsi_tcp: update outdated comment for renamed iscsi_conn_set_callbacks()

scsi: iscsi_tcp: update outdated comment for renamed iscsi_conn_set_callbacks()

The function iscsi_conn_set_callbacks() was renamed to
iscsi_sw_tcp_conn_set_callbacks() by commit 38e1a8f5479d ("[SCSI]
iscsi_tcp: hook iscsi_tcp into new libiscsi_tcp module").  Update the
stale reference in iscsi_sw_tcp_conn_restore_callbacks().

Assisted-by: unnamed:deepseek-v3.2 coccinelle
Signed-off-by: Kexin Sun <kexinsun@smail.nju.edu.cn>
Link: https://patch.msgid.link/20260321105904.7726-1-kexinsun@smail.nju.edu.cn
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>