Fix warnings in frameworks/native/services/surfaceflinger/tests/fakehwc

* Fix typo.
* Ignore returned value of registerAsService?

Bug: 66996870
Test: build with WITH_TIDY=1
Change-Id: I0d9f4372e493547f908f02b07728295bac7d4be3
diff --git a/services/surfaceflinger/tests/fakehwc/FakeComposerClient.cpp b/services/surfaceflinger/tests/fakehwc/FakeComposerClient.cpp
index 60916f3..561db8d 100644
--- a/services/surfaceflinger/tests/fakehwc/FakeComposerClient.cpp
+++ b/services/surfaceflinger/tests/fakehwc/FakeComposerClient.cpp
@@ -582,7 +582,7 @@
 }
 
 void FakeComposerClient::onSurfaceFlingerStart() {
-    mSurfaceComposer == nullptr;
+    mSurfaceComposer = nullptr;
     do {
         mSurfaceComposer = new android::SurfaceComposerClient;
         android::status_t initResult = mSurfaceComposer->initCheck();