tcg-arm: Cleanup multiply subroutines Make the code more readable by only having one copy of the magic numbers, swapping registers as needed prior to that. Speed the compiler by not applying the rd == rn avoidance for v6 or later. Reviewed-by: Aurelien Jarno <aurelien@aurel32.net> Signed-off-by: Richard Henderson <rth@twiddle.net>