riscv: Fix the RVV build

Use the correct RVV intrinsic, i.e.,
`__riscv_vaaddu_vv_u8m1` instead of `__riscv_vaaddu_wx_u8m1`.

Reviewed-by: Cosmin Truta <ctruta@gmail.com>
Signed-off-by: Cosmin Truta <ctruta@gmail.com>
1 file changed