drm/i915: Move i915_ppgtt_close() into i915_gem_gtt.c

Move it alongside its ppgtt counterparts, in order to make it available
for the ppgtt selftests.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170111210937.29252-26-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
3 files changed