greybus: connection: add functions to get/set private data

Add gb_connection_get_data() and gb_connection_set_data() to get and set
the private data of a connection, instead of "open coding" it
everywhere.
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/connection.h

@@ -88,4 +88,15 @@ static inline bool gb_connection_e2efc_enabled(struct gb_connection *connection)
 	return !(connection->flags & GB_CONNECTION_FLAG_CSD);
 }
 
+static inline void *gb_connection_get_data(struct gb_connection *connection)
+{
+	return connection->private;
+}
+
+static inline void gb_connection_set_data(struct gb_connection *connection,
+					  void *data)
+{
+	connection->private = data;
+}
+
 #endif /* __CONNECTION_H */