sim: correct check for endianess
sim: correct check for endianess

Committed by: Nilay Vaish <nilay@cs.wisc.edu>
(transplanted from 20686329e67335885ee645655494e5ec952ff615)

andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin