Comment # 21 on bug 1174622 from Takashi Iwai

FWIW, a simple workaround would be to create a script
/usr/lib/systemd/system-sleep/iwlwifi-reload.sleep, containing the content
like:

#!/bin/sh
if [ "$1" = "pre" ]; then
    modprobe -r iwlmvm
else
    modprobe iwlwifi
fi
exit 0