target/riscv: Add support for Zve32x extension

target/riscv: Add support for Zve32x extension

Add support for Zve32x extension and replace some checks for Zve32f with
Zve32x, since Zve32f depends on Zve32x.

Signed-off-by: Jason Chien <jason.chien@sifive.com>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Max Chou <max.chou@sifive.com>
Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Message-ID: <20240328022343.6871-2-jason.chien@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>