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/DisplayHardware/HWComposer.cpp b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
index 0c29569..bac24c7 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
@@ -380,20 +380,20 @@
     return mDisplayData.at(displayId).hwcDisplay->isVsyncPeriodSwitchSupported();
 }
 
-status_t HWComposer::getDisplayVsyncPeriod(PhysicalDisplayId displayId,
-                                           nsecs_t* outVsyncPeriod) const {
-    RETURN_IF_INVALID_DISPLAY(displayId, 0);
+ftl::Expected<nsecs_t, status_t> HWComposer::getDisplayVsyncPeriod(
+        PhysicalDisplayId displayId) const {
+    RETURN_IF_INVALID_DISPLAY(displayId, ftl::Unexpected(BAD_INDEX));
 
     if (!isVsyncPeriodSwitchSupported(displayId)) {
-        return INVALID_OPERATION;
+        return ftl::Unexpected(INVALID_OPERATION);
     }
+
     const auto hwcId = *fromPhysicalDisplayId(displayId);
     Hwc2::VsyncPeriodNanos vsyncPeriodNanos = 0;
-    auto error =
+    const auto error =
             static_cast<hal::Error>(mComposer->getDisplayVsyncPeriod(hwcId, &vsyncPeriodNanos));
-    RETURN_IF_HWC_ERROR(error, displayId, 0);
-    *outVsyncPeriod = static_cast<nsecs_t>(vsyncPeriodNanos);
-    return NO_ERROR;
+    RETURN_IF_HWC_ERROR(error, displayId, ftl::Unexpected(UNKNOWN_ERROR));
+    return static_cast<nsecs_t>(vsyncPeriodNanos);
 }
 
 std::vector<ui::ColorMode> HWComposer::getColorModes(PhysicalDisplayId displayId) const {