drm/i915: Emit a user level message when resetting the GPU (or engine)

drm/i915: Emit a user level message when resetting the GPU (or engine)

Although a banned context will be told to -EIO off if they try to submit
more requests, we have a discrepancy between whole device resets and
per-engine resets where we report the GPU reset but not the engine
resets. This leaves a bit of mystery as to why the context was banned,
and also reduces awareness overall of when a GPU (engine) reset occurs
with its possible side-effects.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Michel Thierry <michel.thierry@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Michel Thierry <michel.thierry@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170721123238.16428-13-chris@chris-wilson.co.uk
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>