Limit HLG to 4.926x SDR

HLG is universally too bright on basically every single platform that
supports HDR. Fix this for Android.

Bug: 362510107
Flag: com.android.graphics.surfaceflinger.flags.begone_bright_hlg
Test: HLG playback
Change-Id: I5d464c016be62b11f6a3cc1ab228e14d198afb15
diff --git a/services/surfaceflinger/surfaceflinger_flags_new.aconfig b/services/surfaceflinger/surfaceflinger_flags_new.aconfig
index d4250bc..1188435 100644
--- a/services/surfaceflinger/surfaceflinger_flags_new.aconfig
+++ b/services/surfaceflinger/surfaceflinger_flags_new.aconfig
@@ -35,6 +35,14 @@
 } # arr_surfacecontrol_setframerate_api
 
 flag {
+  name: "begone_bright_hlg"
+  namespace: "core_graphics"
+  description: "Caps HLG brightness relative to SDR"
+  bug: "362510107"
+  is_fixed_read_only: true
+} # begone_bright_hlg
+
+flag {
   name: "ce_fence_promise"
   namespace: "window_surfaces"
   description: "Moves logic for buffer release fences into LayerFE"