drm/i915: Remove i915_address_space.start

Once upon a time, back in the UMS days, we supported userspace
initialising the GTT and sharing portions of the GTT with other users.
Now, we own the GTT (both global and per-process) and the tables always
start at 0 - so we can remove i915_address_space.start and forget about
this old complication.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170215084357.19977-20-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/i915_gem_evict.c b/drivers/gpu/drm/i915/i915_gem_evict.c
index ca25b1f..a0de573 100644
--- a/drivers/gpu/drm/i915/i915_gem_evict.c
+++ b/drivers/gpu/drm/i915/i915_gem_evict.c
@@ -274,7 +274,7 @@ int i915_gem_evict_for_node(struct i915_address_space *vm,
 	check_color = vm->mm.color_adjust;
 	if (check_color) {
 		/* Expand search to cover neighbouring guard pages (or lack!) */
-		if (start > vm->start)
+		if (start)
 			start -= I915_GTT_PAGE_SIZE;
 
 		/* Always look at the page afterwards to avoid the end-of-GTT */