sdm: comply with treble guidelines

Modify the property names and use macros in place of them

CRs-Fixed: 2206249
Change-Id: I5ae790ca62a258b0d7c14931e0132727feed48a3
diff --git a/sdm/libs/hwc2/cpuhint.cpp b/sdm/libs/hwc2/cpuhint.cpp
index 551fa24..ca88ead 100644
--- a/sdm/libs/hwc2/cpuhint.cpp
+++ b/sdm/libs/hwc2/cpuhint.cpp
@@ -46,7 +46,7 @@
   }
 
   int pre_enable_window = -1;
-  debug_handler->GetProperty("sdm.perf_hint_window", &pre_enable_window);
+  debug_handler->GetProperty(PERF_HINT_WINDOW_PROP, &pre_enable_window);
   if (pre_enable_window <= 0) {
     DLOGI("Invalid CPU Hint Pre-enable Window %d", pre_enable_window);
     return kErrorNotSupported;