drm/i915: Include the HW breadcrumb whenever we trace the global_seqno

When we include a request's global_seqno in a GEM_TRACE it often helps
to know how that relates to the current breadcrumb as seen by the
hardware.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180327210157.16896-3-chris@chris-wilson.co.uk
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>