well, firstly, even if it's not a gaming laptop, it should still run BF3 on low settings at around 30 fps. There's no reason why it cannot do it.
Secondly, there's a hybrid crossfire mode that should be applicable in your situation, which will allow the integrated GPu to render 1 frame for every 3 the dedicated one renders.
This is what I'm referring to:http://www.notebookcheck.net/AMD-Radeon-HD-6755G2.57278.0.html
Here's a link that explains how to make sure the asymmetric crossfire is on:http://www.techspot.com/community/topics/apus-dual-graphics-how-to-enable-crossfire.178176/
(coincidentally the same model as yours)
It might give you a little bit better performance to make the game bearable. But first and foremost, make sure you are not trying to run it at resolution higher than 1280x720