drm/i915: Add engine reset count to error state

Driver maintains count of how many times a given engine is reset, useful to
capture this in error state also. It gives an idea of how engine is coping
up with the workloads it is executing before this error state.

A follow-up patch will provide this information in debugfs.

v2: s/engine_reset/reset_engine/ (Chris)
    Define count as unsigned int (Tvrtko)

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Signed-off-by: Arun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: Michel Thierry <michel.thierry@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170615201828.23144-7-michel.thierry@intel.com


Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/20170620095751.13127-7-chris@chris-wilson.co.uk