STM32L4 alarm may not work

[dhalbert]

@Vindictive Pigeon in discord reports alarm, including time alarms, doesn't seem to work on the Swan R5, an STM32L4R5 board.

@m-mcgowan: may be of interest to you.

[bablokb]

Probably the same as #8977? I added some graphs there (using time-alarms).