drm/i915/huc: Assert that HuC vma is placed in GuC accessible range

HuC firmware is mapped at GuC accessible range. Let's add an assert to
verify that.

Cc: Anusha Srivatsa <anusha.srivatsa@intel.com>
Cc: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170120192348.2049-2-michal.winiarski@intel.comSigned-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/intel_huc.c

@@ -312,7 +312,7 @@ void intel_guc_auth_huc(struct drm_i915_private *dev_priv)
 
 	/* Specify auth action and where public signature is. */
 	data[0] = INTEL_GUC_ACTION_AUTHENTICATE_HUC;
-	data[1] = i915_ggtt_offset(vma) + huc->fw.rsa_offset;
+	data[1] = guc_ggtt_offset(vma) + huc->fw.rsa_offset;
 
 	ret = intel_guc_send(guc, data, ARRAY_SIZE(data));
 	if (ret) {