drm/i915/guc: Support for extended GuC notification messages

GuC may send notification messages with payload larger than
single u32. Prepare driver to accept longer messages.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Cc: Michal Winiarski <michal.winiarski@intel.com>
Cc: Tomasz Lis <tomasz.lis@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190321120004.53012-1-michal.wajdeczko@intel.com

drivers/gpu/drm/i915/intel_guc.h

@@ -165,7 +165,8 @@ int intel_guc_send_mmio(struct intel_guc *guc, const u32 *action, u32 len,
 void intel_guc_to_host_event_handler(struct intel_guc *guc);
 void intel_guc_to_host_event_handler_nop(struct intel_guc *guc);
 void intel_guc_to_host_event_handler_mmio(struct intel_guc *guc);
-void intel_guc_to_host_process_recv_msg(struct intel_guc *guc, u32 msg);
+int intel_guc_to_host_process_recv_msg(struct intel_guc *guc,
+				       const u32 *payload, u32 len);
 int intel_guc_sample_forcewake(struct intel_guc *guc);
 int intel_guc_auth_huc(struct intel_guc *guc, u32 rsa_offset);
 int intel_guc_suspend(struct intel_guc *guc);