dt-bindings, firmware: add Intel Stratix10 service layer binding

Add a device tree binding for the Intel Stratix10 service layer driver

Signed-off-by: Richard Gong <richard.gong@intel.com>
Signed-off-by: Alan Tull <atull@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Moritz Fischer <mdf@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>