Update cellVoice.cpp

Caused warnings. Not sure what the actual intention was, this may need to be inverted.
This commit assumes that erase() returning 0 is a sign that deletion
failed, or that there was corruption. There should be a port there.

rpcs3/Emu/Cell/Modules/cellVoice.cpp

@@ -194,7 +194,7 @@ error_code cellVoiceDeletePort(u32 portId)
 	if (!manager->is_init)
 		return CELL_VOICE_ERROR_LIBVOICE_NOT_INIT;
 
-	if (!manager->ports.erase((u16)portId) == 0)
+	if (manager->ports.erase((u16)portId) == 0)
 		return CELL_VOICE_ERROR_TOPOLOGY;
 
 	return CELL_OK;