Use HWC_DISPLAY_PRIMARY and _EXTERNAL

Some of the code in the SurfaceFlinger and VR composer assume that the
composer has display IDs HWC_DISPLAY_PRIMARY and HWC_DISPLAY_EXTERNAL
for those specific displays. Modify test to follow the requirement.

Bug: 64446190
Test: Run the test on Marlin
Change-Id: I7fef17158d62bd7cd242b97d37724a229f9c7418
diff --git a/services/surfaceflinger/tests/fakehwc/FakeComposerClient.cpp b/services/surfaceflinger/tests/fakehwc/FakeComposerClient.cpp
index 60916f3..d97ffa3 100644
--- a/services/surfaceflinger/tests/fakehwc/FakeComposerClient.cpp
+++ b/services/surfaceflinger/tests/fakehwc/FakeComposerClient.cpp
@@ -36,7 +36,6 @@
 #include <thread>
 
 constexpr Config NULL_DISPLAY_CONFIG = static_cast<Config>(0);
-constexpr Display DEFAULT_DISPLAY = static_cast<Display>(1);
 
 using namespace sftest;
 
@@ -168,7 +167,7 @@
     ALOGV("enableCallback");
     mCallbacksOn = enable;
     if (mCallbacksOn) {
-        mClient->onHotplug(DEFAULT_DISPLAY, IComposerCallback::Connection::CONNECTED);
+        mClient->onHotplug(PRIMARY_DISPLAY, IComposerCallback::Connection::CONNECTED);
     }
 }
 
@@ -507,7 +506,7 @@
         if (mSurfaceComposer != nullptr) {
             mSurfaceComposer->injectVSync(timestamp);
         } else {
-            mClient->onVsync(DEFAULT_DISPLAY, timestamp);
+            mClient->onVsync(PRIMARY_DISPLAY, timestamp);
         }
     }
 }