drm/i915: Program EXT2 GC MAX registers

EXT2 GC MAX registers are introduced from Gen10+ to
program values from 3.0 to 7.0. Enabled the same, but
currently limiting it to 1.0 as userspace ABI is limited
at that currently.

v2: Updated the 1.0 programming and aligned as per GLK, also added
GLK along with GEN10+ check, as per Ville's feedback.

Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1553869756-4546-3-git-send-email-uma.shankar@intel.com