platform/x86/intel/sdsi: Set message size during writes

platform/x86/intel/sdsi: Set message size during writes

New mailbox commands will support sending multi packet writes and updated
firmware now requires that the message size be written for all commands
along with the packet size. Since the driver doesn't perform writes larger
than the packet size, set the message size to the same value.

Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Link: https://lore.kernel.org/r/20240411025856.2782476-2-david.e.box@linux.intel.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>