target/riscv: Use check for relationship between Zdinx/Zhinx{min} and Zfinx

target/riscv: Use check for relationship between Zdinx/Zhinx{min} and Zfinx

Zdinx/Zhinx{min} require Zfinx. And require relationship is usually done
by check currently.

Signed-off-by: Weiwei Li <liweiwei@iscas.ac.cn>
Signed-off-by: Junqiang Wang <wangjunqiang@iscas.ac.cn>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20230408135908.25269-1-liweiwei@iscas.ac.cn>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>