drm/i915/gt: Also use async bind for PIN_USER into bsw/bxt ggtt

In the rare cases where we are using the global GGTT for execution in
the selftests, we have marked them with PIN_USER knowing that they will
be bound as PIN_GLOBAL as well. However, we need to catch the extra flag
in deciding to use the async worker for such binds as well.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200131081543.2251298-1-chris@chris-wilson.co.uk