drm/i915: Use the vma resource as argument for gtt binding / unbinding

When introducing asynchronous unbinding, the vma itself may no longer
be alive when the actual binding or unbinding takes place.

Update the gtt i915_vma_ops accordingly to take a struct i915_vma_resource
instead of a struct i915_vma for the bind_vma() and unbind_vma() ops.
Similarly change the insert_entries() op for struct i915_address_space.

Replace a couple of i915_vma_snapshot members with their newly introduced
i915_vma_resource counterparts, since they have the same lifetime.

Also make sure to avoid changing the struct i915_vma_flags (in particular
the bind flags) async. That should now only be done sync under the
vm mutex.

v2:
- Update the vma_res::bound_flags when binding to the aliased ggtt
v6:
- Remove I915_VMA_ALLOC_BIT (Matthew Auld)
- Change some members of struct i915_vma_resource from unsigned long to u64
  (Matthew Auld)
v7:
- Fix vma resource size parameters to be u64 rather than unsigned long
  (Matthew Auld)

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220110172219.107131-3-thomas.hellstrom@linux.intel.com

drivers/gpu/drm/i915/i915_vma.h

@@ -339,12 +339,6 @@ void __iomem *i915_vma_pin_iomap(struct i915_vma *vma);
  */
 void i915_vma_unpin_iomap(struct i915_vma *vma);
 
-static inline struct page *i915_vma_first_page(struct i915_vma *vma)
-{
-	GEM_BUG_ON(!vma->pages);
-	return sg_page(vma->pages->sgl);
-}
-
 /**
  * i915_vma_pin_fence - pin fencing state
  * @vma: vma to pin fencing for
@@ -445,6 +439,11 @@ i915_vma_get_current_resource(struct i915_vma *vma)
 	return i915_vma_resource_get(vma->resource);
 }
 
+#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
+void i915_vma_resource_init_from_vma(struct i915_vma_resource *vma_res,
+				     struct i915_vma *vma);
+#endif
+
 void i915_vma_module_exit(void);
 int i915_vma_module_init(void);