ChargingControl: Use ServiceManager.waitForDeclaredService()

It might take a while until health HAL is up, thus let's just wait for
it.

Change-Id: Ie929a25a2a774aedb4559662e9ad0a47f1b154e6
diff --git a/src/org/omnirom/omnilib/internal/health/ChargingControlController.java b/src/org/omnirom/omnilib/internal/health/ChargingControlController.java
index a278802..71e4a05 100644
--- a/src/org/omnirom/omnilib/internal/health/ChargingControlController.java
+++ b/src/org/omnirom/omnilib/internal/health/ChargingControlController.java
@@ -143,7 +143,8 @@
 
         mContentResolver = mContext.getContentResolver();
         mChargingControl = IChargingControl.Stub.asInterface(
-                ServiceManager.getService(IChargingControl.DESCRIPTOR + "/default"));
+                ServiceManager.waitForDeclaredService(
+                        IChargingControl.DESCRIPTOR + "/default"));
 
         if (mChargingControl == null) {
             Log.i(TAG, "OmniRom Health HAL not found");