drm/i915/vlv: remove wait for previous GFX clk disable request

Looks like it was introduced in:

commit 650ad970
Author: Imre Deak <imre.deak@intel.com>
Date:   Fri Apr 18 16:35:02 2014 +0300

    drm/i915: vlv: factor out vlv_force_gfx_clock and check for pending force-of

but I'm not sure why.  It has caused problems for us in the past (see
85250ddf "drm/i915/chv: Remove Wait for a previous gfx force-off"
and 8d4eee9c "drm/i915: vlv: increase timeout when forcing on the
GFX clock") and doesn't seem to be required, so let's just drop it.

References: https://bugs.freedesktop.org/show_bug.cgi?id=89611


Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: Darren Hart <dvhart@linux.intel.com>
Reviewed-by: Deepak S <deepak.s@linux.intel.com>
Cc: stable@vger.kernel.org # c9c52e24: drm/i915/chv: Remove Wait ...
Cc: stable@vger.kernel.org
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
[danvet: Repick this commit from
5df0582b becuase Dave Airlie lost it
in his merge commit e1dee197.]
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>