target/riscv: Add CTR sctrclr instruction.

target/riscv: Add CTR sctrclr instruction.

CTR extension adds a new instruction sctrclr to quickly
clear the recorded entries buffer.

Signed-off-by: Rajnesh Kanwal <rkanwal@rivosinc.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20250205-b4-ctr_upstream_v6-v6-5-439d8e06c8ef@rivosinc.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>