drm/i915: Remove incorrect warning in context cleanup

drm/i915: Remove incorrect warning in context cleanup

Commit e9f24d5fb7cf3628b195b18ff3ac4e37937ceeae
Author: Tvrtko Ursulin <[email protected]>
Date:   Mon Oct 5 13:26:36 2015 +0100

    drm/i915: Clean up associated VMAs on context destruction

Added a warning based on an incorrect assumption that all VMAs
in a VM will be on the inactive list at the point last reference
to a context and VM is dropped.

This is not true because i915_gem_object_retire__read will not
put VMA on the inactive list until all activities on the object
in question (in all VMs) have been retired.

As a consequence, whether or not a context/VM will be destroyed
with its VMAs still on the active list, can depend on completely
unrelated activities using the same object from a different
context or engine.

Signed-off-by: Tvrtko Ursulin <[email protected]>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92638
Testcase: igt/gem_request_retire/retire-vma-not-inactive
Cc: Daniel Vetter <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Michel Thierry <[email protected]>
Link: http://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Daniel Vetter <[email protected]>
(cherry picked from commit 408952d43b27a54437244c56c0e0d8efa5607926)
Signed-off-by: Jani Nikula <[email protected]>