SF: Remove conditional lock in setPowerMode

The mCurrentState access in setPowerModeInternal was only for looking up
the sequence ID of the display.

Bug: 74619554
Test: Boot
Change-Id: If0fad8f19bf8680f247476c3ffe52667e061fdd3
diff --git a/services/surfaceflinger/DisplayDevice.h b/services/surfaceflinger/DisplayDevice.h
index 8357228..ba85432 100644
--- a/services/surfaceflinger/DisplayDevice.h
+++ b/services/surfaceflinger/DisplayDevice.h
@@ -112,6 +112,7 @@
 
     const std::optional<DisplayId>& getId() const { return mId; }
     const wp<IBinder>& getDisplayToken() const { return mDisplayToken; }
+    int32_t getSequenceId() const { return mSequenceId; }
 
     int32_t getSupportedPerFrameMetadata() const { return mSupportedPerFrameMetadata; }
 
@@ -205,6 +206,7 @@
 private:
     const sp<SurfaceFlinger> mFlinger;
     const wp<IBinder> mDisplayToken;
+    const int32_t mSequenceId;
 
     std::optional<DisplayId> mId;
 
@@ -332,6 +334,7 @@
     const wp<IBinder> displayToken;
     const std::optional<DisplayId> displayId;
 
+    int32_t sequenceId{0};
     bool isVirtual{false};
     bool isSecure{false};
     sp<ANativeWindow> nativeWindow;