RISC-V: Update Scalar Crypto testcases.

RISC-V: Update Scalar Crypto testcases.

Add opcodes in testcases to make sure every instruction generate
right opcode after disassemble.

gas/ChangeLog:

        * testsuite/gas/riscv/k-ext-64.d: Add opcode detect.
        * testsuite/gas/riscv/k-ext.d: Ditto.
        * testsuite/gas/riscv/zbkb-32.d: Ditto.
        * testsuite/gas/riscv/zbkb-64.d: Ditto.
        * testsuite/gas/riscv/zbkc-32.d: Ditto.
        * testsuite/gas/riscv/zbkc-64.d: Ditto.
        * testsuite/gas/riscv/zbkx-32.d: Ditto.
        * testsuite/gas/riscv/zbkx-64.d: Ditto.
        * testsuite/gas/riscv/zknd-32.d: Ditto.
        * testsuite/gas/riscv/zknd-64.d: Ditto.
        * testsuite/gas/riscv/zkne-32.d: Ditto.
        * testsuite/gas/riscv/zkne-64.d: Ditto.
        * testsuite/gas/riscv/zknh-32.d: Ditto.
        * testsuite/gas/riscv/zknh-64.d: Ditto.
        * testsuite/gas/riscv/zksed-32.d: Ditto.
        * testsuite/gas/riscv/zksed-64.d: Ditto.
        * testsuite/gas/riscv/zksh-32.d: Ditto.
        * testsuite/gas/riscv/zksh-64.d: Ditto.