dt-bindings: riscv: Add Zabha ISA extension description

Add description for the Zabha ISA extension which was ratified in April
2024.

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Andrea Parri <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20241103145153.105097-5-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Author: Alexandre Ghiti

Documentation/devicetree/bindings/riscv/extensions.yaml

@@ -178,6 +178,12 @@ properties:
             as ratified at commit 4a69197e5617 ("Update to ratified state") of
             riscv-svvptc.
 
+        - const: zabha
+          description: |
+            The Zabha extension for Byte and Halfword Atomic Memory Operations
+            as ratified at commit 49f49c842ff9 ("Update to Rafified state") of
+            riscv-zabha.
+
         - const: zacas
           description: |
             The Zacas extension for Atomic Compare-and-Swap (CAS) instructions