intel: Allow some codenames in INTEL_DEVID_OVERRIDE

As well as allowing a hexadecimal PCI ID number, the
INTEL_DEVID_OVERRIDE environment variable can now contain one of a few
short codenames. The codenames are stored in a small table to map them
to a corresponding PCI ID. This makes it easier to use without having
to look up the PCI IDs manually.

The PCI IDs used are the same as those chosen for the -p option of
run.c in shader-db but SKL has been added as well.

Reviewed-by: Matt Turner <mattst88@gmail.com>