drm/i915/tgl: add initial Tiger Lake definitions

Tiger Lake is a Intel® Processor containing Intel® HD Graphics.

This is just an initial Tiger Lake definition. PCI IDs, generic support
and new features coming in following patches.

v2 (Lucas):
  - Remove modular FIA - feature will be re-introduced in future

Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190711173115.28296-3-lucas.demarchi@intel.com