Why? Giving it more RAM will do absolutely nothing, its like putting wide racing wheels on a Fiat 500, it doesn't matter how much traction(ram) you give it, you just don't have the horsepower to get good performance out of it.
Your system will dynamically assign memory to the IGP based on what is available and what it needs, your IGP will never be memory starved primarily because it doesn't have the computational power to be able to need more than about 512MB of VRAM.