drm/i915/execlists: Fixup cancel_port_requests()

drm/i915/execlists: Fixup cancel_port_requests()

I rushed a last minute correction to cancel_port_requests() to prevent
the snooping of *execlists->active as the inflight array was being
updated, without noticing we iterated the inflight array starting from
active! Oops.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112387
Fixes: 7814e712cb2d ("drm/i915/gt: Mark the execlists->active as the primary volatile access")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191125112520.1760492-1-chris@chris-wilson.co.uk
(cherry picked from commit da0ef77e1e0ccff703efee82406c629d5c4f4bbb)
[Joonas: Fixed Fixes: tag to match drm-intel-next-fixes]
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>