drm/i915: move getting struct_mutex lower in the callstack during GPU reset

Getting struct_mutex around the whole intel_enable_gt_powersave()
function is not necessary, since it's only needed for the ILK path
therein.

This will make intel_enable_gt_powersave() useable on the RPM resume
path for >=GEN6 (added in an upcoming patch to reset the RPS state
during RPM resume), where we can't (and need not) get this mutex.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.c

@@ -781,11 +781,8 @@ int i915_reset(struct drm_device *dev)
 		 * reset and the re-install of drm irq. Skip for ironlake per
 		 * previous concerns that it doesn't respond well to some forms
 		 * of re-init after reset. */
-		if (INTEL_INFO(dev)->gen > 5) {
-			mutex_lock(&dev->struct_mutex);
+		if (INTEL_INFO(dev)->gen > 5)
 			intel_enable_gt_powersave(dev);
-			mutex_unlock(&dev->struct_mutex);
-		}
 
 		intel_hpd_init(dev);
 	} else {