epic100 endianness annotations and fixes

* "powerpc or sparc" is not the same as "big-endian", fix the ifdef
* since we tell the card to byteswap the descriptors on big-endian,
  we ought to leave them host-endian...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jeff Garzik <jeff@garzik.org>