Yocto: Fix build issue in Yocto 64bit.

Signed-off-by: Blance Tang <guofeng.tang@amlogic.com>
Change-Id: I084fa9bd56652668f976bdd47752a53467d182a5
diff --git a/src/audio_server.cpp b/src/audio_server.cpp
index cfc36bf..b79d202 100644
--- a/src/audio_server.cpp
+++ b/src/audio_server.cpp
@@ -693,7 +693,7 @@
       if (stream == nullptr) return Status::CANCELLED;
 
       IpcBuffer *cb = shm_->find<IpcBuffer>(request->name().c_str()).first;
-      response->set_ret(stream->read(stream, cb->start_ptr(), std::min(request->size(), cb->capacity())));
+      response->set_ret(stream->read(stream, cb->start_ptr(), std::min((size_t) request->size(), cb->capacity())));
       return Status::OK;
     }