target/arm: Use expand_pred_b in mve_helper.c

target/arm: Use expand_pred_b in mve_helper.c

Use the function instead of the array directly.

Because the function performs its own masking, via the uint8_t
parameter, we need to do nothing extra within the users: the bits
above the first 2 (_uh) or 4 (_uw) will be discarded by assignment
to the local bmask variables, and of course _uq uses the entire
uint64_t result.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220607203306.657998-17-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>