target/riscv/kvm: add zicntr reg

target/riscv/kvm: add zicntr reg

Add zicntr support in the KVM driver now that QEMU supports it.

This reg was added in Linux 6.6.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20231023153927.435083-3-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>