drm/i915: fix rps.vlv_work initialization

During driver loading we are initializing rps.vlv_work in
valleyview_enable_rps() via the rps.delayed_resume_work delayed work.
This is too late since we are using vlv_work already via
i915_driver_load()->intel_uncore_sanitize()->
intel_disable_gt_powersave(). This at least leads to the following
kernel warning:

 INFO: trying to register non-static key.
 the code is fine but needs lockdep annotation.
 turning off the locking correctness validator.

Fix this by initialzing vlv_work before we call intel_uncore_sanitize().

The regression was introduced in

commit 7dcd2677
Author: Konstantin Khlebnikov <khlebnikov@openvz.org>
Date:   Wed Jul 17 10:22:58 2013 +0400

    drm/i915: fix long-standing SNB regression in power consumption
    after resume

though there was no good reason to initialize the static vlv_work from
another delayed work to begin with (especially since this will happen
multiple times).

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=69397


Tested-by: shui yangwei <yangweix.shui@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>