[adc_ctrl] Periodic scanning fix
[adc_ctrl] Periodic scanning fix

- fixes #11784
- The original intent of the spec was not clear whether periodic scanning
  should trigger on any match or specific debounced matches.
- After going through some of the older documentations, there is no clear
  evidence that "any" was needed, as a result, switch the design to
  debounced checks.

Signed-off-by: Timothy Chen <d7b2ae30d8c0f215facd721941273067fd1d14a2@google.com>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan