drm/i915/gt: Mark ring->vma as active while pinned

drm/i915/gt: Mark ring->vma as active while pinned

As we use the active state to keep the vma alive while we are reading
its contents during GPU error capture, we need to mark the
ring->vma as active during execution if we want to include the rinbuffer
in the error state.

Reported-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Fixes: b1e3177bd1d8 ("drm/i915: Coordinate i915_active with its own mutex")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Acked-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200110110402.1231745-3-chris@chris-wilson.co.uk
(cherry picked from commit 8ccfc20a7d56d7e16510e6e068ffb7b43c3ac100)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>