spi: fsi: fsi2spi: Add compatible string for restricted version

Add a compatible string for the restricted version of the SPI controller.
The restricted version cannot process sequence loop operations and
therefore has a smaller transfer size.
Signed-off-by: Eddie James <eajames@linux.ibm.com>
Link: https://lore.kernel.org/r/20200909222857.28653-5-eajames@linux.ibm.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/fsi/ibm,fsi2spi.yaml

@@ -19,6 +19,7 @@ properties:
   compatible:
     enum:
       - ibm,fsi2spi
+      - ibm,fsi2spi-restricted
 
   reg:
     items: