Implement the MVE insn VMLSLDAV, which multiplies source elements,
alternately adding and subtracting them, and accumulates into a
64-bit result in a pair of general purpose registers.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210617121628.20116-21-peter.maydell@linaro.org