drm/i915/glk: Enable pooled EUs for Geminilake

Geminilake also supports pooled EUs. Enable it.

It is unclear if the recommendation to disable it for 2x6 configurations
from commit e015dd69 ("drm/i915/bxt: Add WaEnablePooledEuFor2x6")
should also apply to GLK, but it is applied anyway to be on the safe
side. That restriction can be lifted later if determined not to impact
performance.

The extra restriction should not impact user space either. The only user
space that uses this feature is Beignet, and it only does so for 3x6
devices. See See Beignet's commit 6901899ec90a ("Runtime: set the sub
slice according to kernel pooled EU configure.").

v2: Improve commit message. (Mika, Roy)

Cc: Arun Siluvery <arun.siluvery@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Yang Rong <rong.r.yang@intel.com>
Signed-off-by: Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170317140436.24645-1-ander.conselvan.de.oliveira@intel.com