Fix clang-tidy warnings in audio and playerservice.

* Add explicit keyword to conversion constructors.
Bug: 28341362
* Use const reference type for read-only parameters.
Bug: 30407689
Test: build with WITH_TIDY=1

Change-Id: I265f3b094e08d5705b506b3fbba51439c134af84
diff --git a/services/audioflinger/Effects.h b/services/audioflinger/Effects.h
index 322c06a..626fcc1 100644
--- a/services/audioflinger/Effects.h
+++ b/services/audioflinger/Effects.h
@@ -358,7 +358,7 @@
     // types or implementations from the suspend/restore mechanism.
     bool isEffectEligibleForSuspend(const effect_descriptor_t& desc);
 
-    void clearInputBuffer_l(sp<ThreadBase> thread);
+    void clearInputBuffer_l(const sp<ThreadBase>& thread);
 
     void setThread(const sp<ThreadBase>& thread);