trans_rvv.c.inc: set vstart = 0 in int scalar move insns

trans_rvv.c.inc: set vstart = 0 in int scalar move insns

trans_vmv_x_s, trans_vmv_s_x, trans_vfmv_f_s and trans_vfmv_s_f aren't
setting vstart = 0 after execution. This is usually done by a helper in
vector_helper.c but these functions don't use helpers.

We'll set vstart after any potential 'over' brconds, and that will also
mandate a mark_vs_dirty() too.

Fixes: dedc53cbc9 ("target/riscv: rvv-1.0: integer scalar move instructions")
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: <20240314175704.478276-3-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>