drm/i915/pmu: Add a name to the execlists stats

In preparation for GuC pmu stats, add a name to the execlists stats
structure so that it can be differentiated from the GuC stats.

Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211027004821.66097-1-umesh.nerlige.ramappa@intel.com

drm/i915/gt: Convert stats.active to plain unsigned int

As context-in/out is now always serialised, we do not have to worry
about concurrent enabling/disable of the busy-stats and can reduce the
atomic_t active to a plain unsigned int, and the seqlock to a seqcount.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210115142331.24458-3-chris@chris-wilson.co.uk

drm/i915/gt: Extract busy-stats for ring-scheduler

Lift the busy-stats context-in/out implementation out of intel_lrc, so
that we can reuse it for other scheduler implementations.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210115142331.24458-2-chris@chris-wilson.co.uk