drm/i915/gem: Leave reloading kernel context on resume to GT

As we already do reload the kernel context in intel_gt_resume, repeating
that action inside i915_gem_resume() as well is redundant.

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/20191101141009.15581-2-chris@chris-wilson.co.uk