SF: Use consistent names for display references

This CL renames IBinder tokens to "displayToken", and DisplayDevice
references to "display". It also cleans up style for affected lines.

Bug: 74619554
Test: Build
Change-Id: I04fc7264bf2a856caf30d662029b6f603f432938
diff --git a/services/surfaceflinger/DisplayDevice.cpp b/services/surfaceflinger/DisplayDevice.cpp
index e7d07e3..39d0507 100644
--- a/services/surfaceflinger/DisplayDevice.cpp
+++ b/services/surfaceflinger/DisplayDevice.cpp
@@ -436,8 +436,8 @@
     return mPowerMode;
 }
 
-bool DisplayDevice::isDisplayOn() const {
-    return (mPowerMode != HWC_POWER_MODE_OFF);
+bool DisplayDevice::isPoweredOn() const {
+    return mPowerMode != HWC_POWER_MODE_OFF;
 }
 
 // ----------------------------------------------------------------------------