drm/i915: Don't fiddle with rps/rc6 across GPU reset

Resetting the GPU doesn't affect the RPS/RC6 state, so we can stop
forcibly reloading the registers.

Ville suggested this many moons ago, I said at that time that sanitizing
was no harm and meant that our bookkeeping was kept consistent with the
HW. However, in a forthcoming series, we want to split rps/rc6 GT
powermanagement and one of the key simplifications is the control of
when we enable it. Performing a crude sanitize in the middle of
i915_gem_reset() is then a huge wart.

Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180410133354.13425-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_gem.c

@@ -3254,13 +3254,6 @@ void i915_gem_reset(struct drm_i915_private *dev_priv,
 	}
 
 	i915_gem_restore_fences(dev_priv);
-
-	if (dev_priv->gt.awake) {
-		intel_sanitize_gt_powersave(dev_priv);
-		intel_enable_gt_powersave(dev_priv);
-		if (INTEL_GEN(dev_priv) >= 6)
-			gen6_rps_busy(dev_priv);
-	}
 }
 
 void i915_gem_reset_finish_engine(struct intel_engine_cs *engine)