#ifdef is not needed here (try not to put #ifdef in .c files.)  I think
a few of your other usages of #ifdef in this file can also be removed
with judicious use of inline functions in a .h file.

ACK on all the ifdef comments.  I may have gone a little ifdef crazy
making sure I could get to a zero impact state with these patches
applied but CONFIG_NET_DMA turned off.  I'll get these cleaned up.

- Chris