avx2: replace invalid macro name with the correct one
avx2: replace invalid macro name with the correct one

X and K are right next to eachother on dvorak, and they look similar
enough that I didn't notice it.  Oops.  I also had to fix a few
functions and macros that broke now that we're actually using the
native functions.

nemequ/simde,nemequ/simde,nemequ/simde