Radeon HD 3870 X2 Open-Source Support

In a git commit this afternoon by Joachim Deguara, an AMD Linux software engineer, support for the new Radeon HD 3870 X2 has been added. As we shared yesterday, the Radeon HD 3870 X2 is the new high-end ATI graphics card but is composed of two Radeon HD 3870 GPU cores. The problem for Linux users, however, boils down to the lack of CrossFire support under Linux in both the open and closed source drivers. This git commit simply adds in the PCI ID and other standard information about the graphics card. The RadeonHD driver will only take advantage of one of the GPUs, thereby defeating the benefits of the X2 over the vanilla HD 3870.