What driver is this from? Unfortunately if they've locked it in little endian, there's not really much you can do, as the card is probably expecting the least significant byte first. You always swap the each word around after you e read it, to make it MSB first, however if you know you're in little endian mode already there shouldn't be a problem.

Just out of curiosity, why do you want to read the data as big endian?

EDIT: Sorry for the necro, I just realized the post was a year old....