wifi: iwlegacy: convert to use secs_to_jiffies()

Since secs_to_jiffies()(commit:b35108a5) has been introduced, we can
use it to avoid scaling the time to msec.

Signed-off-by: Yuesong Li <liyuesong@vivo.com>
Acked-by: Stanislaw Gruszka <stf_xl@wp.pl>
Link: https://patch.msgid.link/20250612021446.3465972-1-liyuesong@vivo.com


Signed-off-by: Johannes Berg <johannes.berg@intel.com>