[Intel-gfx] Please, add has_fbc = 1 for 915GM chipset

[SD]

Please, add support for 915GM chipset.
My card is:

[    0.100352] pci 0000:00:02.0: [8086:2592] type 0 class 0x000300
[    0.100431] pci 0000:00:02.1: [8086:2792] type 0 class 0x000380


Thank you.