spi: add generic R-Car Gen4 and specific r8a779f0 support

Merge series from Wolfram Sang <wsa+renesas@sang-engineering.com>:

Here are the patches to enable MSIOF on R-Car S4-8. They also introduce
generic Gen4 support and move V3U to Gen4 (which it really is).

Documentation/devicetree/bindings/spi/renesas,sh-msiof.yaml

@@ -47,9 +47,14 @@ properties:
               - renesas,msiof-r8a77980      # R-Car V3H
               - renesas,msiof-r8a77990      # R-Car E3
               - renesas,msiof-r8a77995      # R-Car D3
-              - renesas,msiof-r8a779a0      # R-Car V3U
           - const: renesas,rcar-gen3-msiof  # generic R-Car Gen3 and RZ/G2
                                             # compatible device
+      - items:
+          - enum:
+              - renesas,msiof-r8a779a0      # R-Car V3U
+              - renesas,msiof-r8a779f0      # R-Car S4-8
+          - const: renesas,rcar-gen4-msiof  # generic R-Car Gen4
+                                            # compatible device
       - items:
           - const: renesas,sh-msiof  # deprecated
 

drivers/spi/spi-sh-msiof.c

@@ -1085,6 +1085,7 @@ static const struct of_device_id sh_msiof_match[] = {
 	{ .compatible = "renesas,rcar-gen2-msiof", .data = &rcar_gen2_data },
 	{ .compatible = "renesas,msiof-r8a7796",   .data = &rcar_gen3_data },
 	{ .compatible = "renesas,rcar-gen3-msiof", .data = &rcar_gen3_data },
+	{ .compatible = "renesas,rcar-gen4-msiof", .data = &rcar_gen3_data },
 	{ .compatible = "renesas,sh-msiof",        .data = &sh_data }, /* Deprecated */
 	{},
 };