google_platform acquired a dependency on protobuf.

Needed to compile vendor/google/platform/rcu_audio. b/33070819

Change-Id: Ie12091d09728920ad575d82166d97747410661fb
diff --git a/package/google/google_platform/Config.in b/package/google/google_platform/Config.in
index 8d0ca58..d19a1ae 100644
--- a/package/google/google_platform/Config.in
+++ b/package/google/google_platform/Config.in
@@ -24,6 +24,7 @@
 	select BR2_PACKAGE_LIBJSONCPP
 	select BR2_PACKAGE_GPERF
 	select BR2_PACKAGE_PY_TORNADO
+	select BR2_PACKAGE_PROTOBUF
 	help
 	  This package is a placeholder that depends on other packages needed
 	  to run the Google Fiber devices.