drm/i915: s/i915_gem_do_init/i915_gem_init_global_gtt

... because this is what it actually doesn now that we have the global
gtt vs. ppgtt split.

Also move it to the other global gtt functions in i915_gem_gtt.c

Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
4 files changed