dt-bindings: riscv: add Zihintntl ISA extension description

Add description for Zihintntl ISA extension[1].

Link: https://drive.google.com/file/d/13_wsN8YmRfH8YWysFyTX-DjTkCnBd9hj/view [1]
Signed-off-by: Clément Léger <cleger@rivosinc.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20231114141256.126749-15-cleger@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Author: clementleger

Documentation/devicetree/bindings/riscv/extensions.yaml

@@ -339,6 +339,12 @@ properties:
             The standard Zihintpause extension for pause hints, as ratified in
             commit d8ab5c7 ("Zihintpause is ratified") of the riscv-isa-manual.
 
+        - const: zihintntl
+          description:
+            The standard Zihintntl extension for non-temporal locality hints, as
+            ratified in commit 0dc91f5 ("Zihintntl is ratified") of the
+            riscv-isa-manual.
+
         - const: zihpm
           description:
             The standard Zihpm extension for hardware performance counters, as