SF: Fix error handling for getDisplayVsyncPeriod

HWC errors were being converted to a status_t of NO_ERROR.

Bug: 241285876
Test: presubmit
Change-Id: I0fcfa426c795adf55a920729bc613a0cd140e87c
diff --git a/services/surfaceflinger/CompositionEngine/tests/MockHWComposer.h b/services/surfaceflinger/CompositionEngine/tests/MockHWComposer.h
index 351cc53..575a30e 100644
--- a/services/surfaceflinger/CompositionEngine/tests/MockHWComposer.h
+++ b/services/surfaceflinger/CompositionEngine/tests/MockHWComposer.h
@@ -103,7 +103,7 @@
     MOCK_CONST_METHOD0(isUsingVrComposer, bool());
     MOCK_CONST_METHOD1(getDisplayConnectionType, ui::DisplayConnectionType(PhysicalDisplayId));
     MOCK_CONST_METHOD1(isVsyncPeriodSwitchSupported, bool(PhysicalDisplayId));
-    MOCK_CONST_METHOD2(getDisplayVsyncPeriod, status_t(PhysicalDisplayId, nsecs_t*));
+    MOCK_CONST_METHOD1(getDisplayVsyncPeriod, ftl::Expected<nsecs_t, status_t>(PhysicalDisplayId));
     MOCK_METHOD4(setActiveModeWithConstraints,
                  status_t(PhysicalDisplayId, hal::HWConfigId,
                           const hal::VsyncPeriodChangeConstraints&,