gn2bp: Remove unnecessary mkdir in proto module

Test: m cronet_aml_net_isolation_info_proto_gen
Change-Id: I44f90fc1b9d547465542845a705e69c6933c1d68
diff --git a/tools/gn2bp/gen_android_bp b/tools/gn2bp/gen_android_bp
index ffb0741..120728b 100755
--- a/tools/gn2bp/gen_android_bp
+++ b/tools/gn2bp/gen_android_bp
@@ -499,7 +499,7 @@
 
   # In GN builds the proto path is always relative to the output directory
   # (out/tmp.xxx).
-  cmd = ['mkdir -p %s &&' % cpp_out_dir, '$(location aprotoc)']
+  cmd = ['$(location aprotoc)']
   cmd += ['--proto_path=%s/%s' % (tree_path, target.proto_in_dir)]
 
   if buildtools_protobuf_src in target.proto_paths: