dt-bindings: riscv: Add xsfvqmaccdod and xsfvqmaccqoq ISA extension description

Add "xsfvqmaccdod" and "xsfvqmaccqoq" ISA extensions which are provided by
SiFive for int8 matrix multiplication instructions support.

Signed-off-by: Cyan Yang <cyan.yang@sifive.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20250418053239.4351-2-cyan.yang@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Author: cyanyang-sifive

Documentation/devicetree/bindings/riscv/extensions.yaml

@@ -662,6 +662,19 @@ properties:
             Registers in the AX45MP datasheet.
             https://www.andestech.com/wp-content/uploads/AX45MP-1C-Rev.-5.0.0-Datasheet.pdf
 
+        # SiFive
+        - const: xsfvqmaccdod
+          description:
+            SiFive Int8 Matrix Multiplication Extensions Specification.
+            See more details in
+            https://www.sifive.com/document-file/sifive-int8-matrix-multiplication-extensions-specification
+
+        - const: xsfvqmaccqoq
+          description:
+            SiFive Int8 Matrix Multiplication Extensions Specification.
+            See more details in
+            https://www.sifive.com/document-file/sifive-int8-matrix-multiplication-extensions-specification
+
         # T-HEAD
         - const: xtheadvector
           description: