spi: renesas_rpc_spi: Add R-Car Gen3 and RZ/G2 fallback compatibility string

Add fallback compatibility string for R-Car Gen3 and RZ/G2.

Also sorted the compatible string as per SoC ID.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
diff --git a/drivers/spi/renesas_rpc_spi.c b/drivers/spi/renesas_rpc_spi.c
index 3ea59b8..d0ff918 100644
--- a/drivers/spi/renesas_rpc_spi.c
+++ b/drivers/spi/renesas_rpc_spi.c
@@ -448,12 +448,13 @@
 };
 
 static const struct udevice_id rpc_spi_ids[] = {
+	{ .compatible = "renesas,rpc-r7s72100" },
 	{ .compatible = "renesas,rpc-r8a7795" },
 	{ .compatible = "renesas,rpc-r8a7796" },
 	{ .compatible = "renesas,rpc-r8a77965" },
 	{ .compatible = "renesas,rpc-r8a77970" },
 	{ .compatible = "renesas,rpc-r8a77995" },
-	{ .compatible = "renesas,rpc-r7s72100" },
+	{ .compatible = "renesas,rcar-gen3-rpc" },
 	{ }
 };