dt-bindings: riscv: add Zca, Zcf, Zcd and Zcb ISA extension description

Add description for Zca, Zcf, Zcd and Zcb extensions which are part the
Zc* standard extensions for code size reduction. Additional validation
rules are added since Zcb depends on Zca, Zcf, depends on Zca and F, Zcd
depends on Zca and D and finally, Zcf can not be present on rv64.

Signed-off-by: Clément Léger <cleger@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/20240619113529.676940-7-cleger@rivosinc.com


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>