Deprecate getDisplayBrightnessSupport.

Brightness is already a per display capability, we don't need this API.

BUG: 130313275
Test: build
Change-Id: I0a669aca19a2873df41bee82bd0e5e2775af8101
diff --git a/graphics/composer/2.3/IComposerClient.hal b/graphics/composer/2.3/IComposerClient.hal
index 1eea306..4d6f78f 100644
--- a/graphics/composer/2.3/IComposerClient.hal
+++ b/graphics/composer/2.3/IComposerClient.hal
@@ -502,6 +502,10 @@
                        float minLuminance);
 
     /**
+     * Use getDisplayCapabilities instead. If brightness is supported, must return
+     * DisplayCapability::BRIGHTNESS as one of the display capabilities via getDisplayCapabilities.
+     * Only use getDisplayCapabilities as the source of truth to query brightness support.
+     *
      * Gets whether brightness operations are supported on a display.
      *
      * @param display