drm/i915: Move idle checks before intel_engine_init_global_seqno()

intel_engine_init_globa_seqno() may be called from an uncontrolled
set-wedged path where we have given up waiting for broken hw and declare
it defunct. Along that path, any sanity checks that the hw is idle
before we adjust its state will expectedly fail, so we simply cannot.
Instead of asserting inside init_global_seqno, we move them to the
normal caller reset_all_global_seqno() as it handles runtime seqno
wraparound.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170721123238.16428-8-chris@chris-wilson.co.uk


Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>