IMapper: change an error message

Change the error message that prints when IMapper 3.0 isn't present.
The old warning was causing unnecessary concerns.

Bug: 128013727
Test: compile
Change-Id: I197cd953d08a8e9f3bdee92cede973bf1b97dfe2
(cherry picked from commit ccbd24f6336bf7141b9a6e463b89aa027b289bfe)
diff --git a/graphics/composer/2.1/utils/hal/include/composer-hal/2.1/ComposerResources.h b/graphics/composer/2.1/utils/hal/include/composer-hal/2.1/ComposerResources.h
index 1df496c..18d184e 100644
--- a/graphics/composer/2.1/utils/hal/include/composer-hal/2.1/ComposerResources.h
+++ b/graphics/composer/2.1/utils/hal/include/composer-hal/2.1/ComposerResources.h
@@ -44,7 +44,7 @@
         if (mMapper3) {
             return true;
         }
-        ALOGW_IF(!mMapper3, "failed to get mapper 3.0 service");
+        ALOGD_IF(!mMapper3, "failed to get mapper 3.0 service, falling back to mapper 2.0");
 
         mMapper2 = mapper::V2_0::IMapper::getService();
         ALOGE_IF(!mMapper2, "failed to get mapper 2.0 service");