target/riscv/insn_trans/trans_rvv.c.inc: use 'vlenb'

target/riscv/insn_trans/trans_rvv.c.inc: use 'vlenb'

Use s->cfg_ptr->vlenb instead of "s->cfg_ptr->vlen / 8"  and
"s->cfg_ptr->vlen >> 3".

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20240122161107.26737-6-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>