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>
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 4ebb93c..e5b9f08 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4556,9 +4556,11 @@
 	struct drm_i915_private *dev_priv = dev->dev_private;
 
 	if (IS_IRONLAKE_M(dev)) {
+		mutex_lock(&dev->struct_mutex);
 		ironlake_enable_drps(dev);
 		ironlake_enable_rc6(dev);
 		intel_init_emon(dev);
+		mutex_unlock(&dev->struct_mutex);
 	} else if (IS_GEN6(dev) || IS_GEN7(dev)) {
 		/*
 		 * PCU communication is slow and this doesn't need to be