[Intel-gfx] Try to make the device info flags a bit more maintainable

[Damien Lespiau]

Hi,

We had a few places (3) to update every time we wanted to add a device info
flag, somewhat error prone. With this series we just need to touch
DEV_INFO_FOR_EACH_FLAG() to add a flag (patches 1-3).

On top of that, I add two more flags, has_ddi (patch 4) and has_fpga_dbg
(patches 5/6), flags that should slightly ease our next enablings.

All pretty simple changes.

-- 
Damien