SF: Clean up helpers for thread priority

Dedupe error logs and remove otherwise unused return values.

Bug: 342681202
Flag: EXEMPT refactor
Test: m surfaceflinger
Change-Id: I6f68b884c1409f73127c06ed3d091dcbd7bdc264
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 3f454ba..94ad651 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -211,11 +211,9 @@
     SurfaceFlinger(surfaceflinger::Factory&, SkipInitializationTag) ANDROID_API;
     explicit SurfaceFlinger(surfaceflinger::Factory&) ANDROID_API;
 
-    // set main thread scheduling policy
-    static status_t setSchedFifo(bool enabled) ANDROID_API;
-
-    // set main thread scheduling attributes
-    static status_t setSchedAttr(bool enabled);
+    // Set scheduling policy and attributes of main thread.
+    static void setSchedFifo(bool enabled, const char* whence);
+    static void setSchedAttr(bool enabled, const char* whence);
 
     static char const* getServiceName() ANDROID_API { return "SurfaceFlinger"; }