drm/i915: Remove i915_vma_create from VMA API

With the introduce of i915_vma_instance() for obtaining the VMA
singleton for a (obj, vm, view) tuple, we can remove the
i915_vma_create() in favour of a single entry point. We do incur a
lookup onto an empty tree, but the i915_vma_create() were being called
infrequently and during initialisation, so the small overhead is
negligible.

v2: Drop the i915_ prefix from the now static vma_create() function

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170116152131.18089-4-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 0a4728f..17f90c6 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -269,7 +269,7 @@ __create_hw_context(struct drm_i915_private *dev_priv,
 			goto err_out;
 		}
 
-		vma = i915_vma_create(obj, &dev_priv->ggtt.base, NULL);
+		vma = i915_vma_instance(obj, &dev_priv->ggtt.base, NULL);
 		if (IS_ERR(vma)) {
 			i915_gem_object_put(obj);
 			ret = PTR_ERR(vma);