riscv: cpufeature: Fix Zk bundled extension missing Zknh

riscv: cpufeature: Fix Zk bundled extension missing Zknh

The Zk extension is a bundle consisting of Zkn, Zkr, and Zkt. The Zkn
extension itself is a bundle consisting of Zbkb, Zbkc, Zbkx, Zknd, Zkne,
and Zknh.

The current implementation of riscv_zk_bundled_exts manually listed
the dependencies but missed RISCV_ISA_EXT_ZKNH.

Fix this by introducing a RISCV_ISA_EXT_ZKN macro that lists the Zkn
components and using it in both riscv_zk_bundled_exts and
riscv_zkn_bundled_exts.

This adds the missing Zknh extension to Zk and reduces code duplication.

Fixes: 0d8295ed975b ("riscv: add ISA extension parsing for scalar crypto")
Link: https://patch.msgid.link/20231114141256.126749-4-cleger@rivosinc.com/
Signed-off-by: Guodong Xu <guodong@riscstar.com>
Reviewed-by: Clément Léger <cleger@rivosinc.com>
Link: https://patch.msgid.link/20251223-zk-missing-zknh-v1-1-b627c990ee1a@riscstar.com
Signed-off-by: Paul Walmsley <pjw@kernel.org>