pw_digital_io: Remove conditional interrupt disabling requirements

Removes conditional interrupt handler disabling requirements from the
DoEnable and DoSetInterruptHandler private virtual APIs for
concrete implementations. Instead the NVI API first calls
DisableInterruptHandler (or DoEnableInterruptHandler(false)) to
simplify implementations and their requirements.

Change-Id: Ie1855d13f7e1ea688305c5b750c5391ce7e72471
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/187668
Commit-Queue: Auto-Submit <[email protected]>
Pigweed-Auto-Submit: Ewout van Bekkum <[email protected]>
Reviewed-by: Wyatt Hepler <[email protected]>
Reviewed-by: Anton Markov <[email protected]>

pw_digital_io/public/pw_digital_io/digital_io.h

@@ -189,6 +189,7 @@ class DigitalIoOptional {
   /// * @pw_status{OK} - The interrupt handler was cleared.
   /// * Other status codes as defined by the backend.
   Status ClearInterruptHandler() {
+    PW_TRY(DisableInterruptHandler());
     return DoSetInterruptHandler(InterruptTrigger::kActivatingEdge, nullptr);
   }
 
@@ -246,7 +247,12 @@ class DigitalIoOptional {
   /// @returns
   /// * @pw_status{OK} - The line is disabled.
   /// * Other status codes as defined by the backend.
-  Status Disable() { return DoEnable(false); }
+  Status Disable() {
+    if (provides_interrupt()) {
+      PW_TRY(DisableInterruptHandler());
+    }
+    return DoEnable(false);
+  }
 
  private:
   friend class DigitalInterrupt;