What version of the arduino environment are you using, because I can compile w/FastLED 3.1 and Arduino 1.5.5 without any issues. Also - are you sure you don’t have any other copies of FastLED lurking around?
Weird, I have 0 problems compiling with FastLED3.1@Head on Arduino 1.5.8 either. First off, are you sure that you have no other copies of FastLED lurking around in any of the arduino or document directories? Secondly, are you sure you have a full checkout of the FastLED3.1 directory (check for FastLED/platforms/arm/sam/led_sysdefs_arm_sam.h)