MueLu: Fix RefMaxwell for when magnitudeType != double
Created by: etphipp
RefMaxwell was using an array of type magnitudeType to compute the norms of the coordinates array, which is of type double. This changes the array to be of the proper type.
Created by: etphipp
RefMaxwell was using an array of type magnitudeType to compute the norms of the coordinates array, which is of type double. This changes the array to be of the proper type.