spi: dt-bindings: snps,dw-apb-ssi: Add compatible for UltraRISC DP1000 SoC

Add the SoC-specific compatible string and use the generic one as fallback
for the UltraRISC DP1000 SPI controller.

The DP1000 integrates two SPI controllers. SPI0 supports standard, dual
and quad transfers with three native chip-select signals. SPI1 supports
standard transfers with four native chip-select signals.

Both controllers have one register range and separate reference and APB
interface clocks.

Signed-off-by: Jia Wang <wangjia@ultrarisc.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://patch.msgid.link/20260907-ultrarisc-dts-v2-5-5eb4c97477c5@ultrarisc.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml

@@ -44,6 +44,21 @@ allOf:
     else:
       properties:
         starfive,sfc-filter-syscon: false
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: ultrarisc,dp1000-spi
+    then:
+      properties:
+        reg:
+          maxItems: 1
+        clocks:
+          minItems: 2
+        clock-names:
+          minItems: 2
+      required:
+        - clock-names
 
 properties:
   compatible:
@@ -63,6 +78,7 @@ properties:
               - mscc,jaguar2-spi
               - sophgo,sg2042-spi
               - thead,th1520-spi
+              - ultrarisc,dp1000-spi
           - const: snps,dw-apb-ssi
       - description: Vendor controllers compatible with v1.01a
         items: