From what I can gather, the i5-3210m (CPU in that model) is socket G2, and therefore removable. (Just guessing this from a quick google of socket G2). You would probably only be able to upgrade to a chip that that model line was sold with, or that HP specifically say is supported by the motherboard. Not too sure whether you'd need a BIOS update to do this to be honest as I've never done it with that model.
The i5-3210M isn't a terrible chip though, why do you need to upgrade it?