drm/i915: Export per-engine reset count info to debugfs

drm/i915: Export per-engine reset count info to debugfs

A new variable is added to export the reset counts to debugfs, this
includes full gpu reset and engine reset count. This is useful for tests
where they are expected to trigger reset; these counts are checked before
and after the test to ensure the same.

v2: Include reset engine count in i915_engine_info too (Chris).

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/20170615201828.23144-8-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/20170620095751.13127-8-chris@chris-wilson.co.uk