drm/i915: rip out GEM drm feature checks

drm/i915: rip out GEM drm feature checks

We always set it so there's no point in checking. We could
instead add a bit that tells us whether gem is actually
initialized (i.e. either kms or gem_init_ioctl called), but
that's imho not worth it.

So just rip it out.

There's a little change in the wait_ring timeout, but we've never
run with anything else than the 60 second timeout, even on dri1
userspace.

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>