ledstatus: use internally stored state when checking if led is on

LED driver will be removed for Edison.
ledservice should use the internally stored state to check
if LED is on when lights hal is available.
This will fix the weave toggle command issue.

BUG=None

Change-Id: I83086517ad1a066c8212253ac99bd5a92c37a26a

src/ledservice/ledstatus.cpp

@@ -109,6 +109,9 @@ std::vector<bool> LedStatus::GetStatus() const {
 }
 
 bool LedStatus::IsLedOn(size_t index) const {
+  if (lights_hal_)
+    return hal_led_status_[index];
+
   brillo::StreamPtr stream = GetLEDDataStream(index, false);
   if (!stream)
     return false;