In /usr/lib/systemd/system-sleep I have, among others, 10-brcmfmac-suspend.sh:
#!/bin/sh
case $1 in
pre) modprobe -r brcmfmac_wcc brcmfmac ;;
post) modprobe brcmfmac_wcc ;;
esac
The first argument to the modprobe -r (brcmfmac_wcc) must be added to make the notebook go to sleep and resume successfully.
At least now it goes to sleep and resumes.
Edit: change to the module to be loaded is brcmfmac_wcc which automatically loads the brcmfmac.