PCI version of Prism2.5/3 has undocumented DMA support for TX/RX data,
but this seems to have some hardware bugs that prevent it from being
used properly for TX. RX side could possibly be made to work reliably.

Even though DMA support would be very useful for saving host CPU (from
about 40% to 5-10% when operating at maximum throughput), it seems to
be best to just remove this code finally. The implementation has
always been commented out by default and has received very limited
testing. The code may have already been broken number of times and I
don't have much interested in trying to verify whether it works or
not. Getting this out makes it easier to maintain the driver and
allows some cleanups that have been partly postponed because of this
experimental bus master/DMA code.

Signed-off-by: Jouni Malinen <jkmaline@cc.hut.fi>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>