More DMA API junk

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

While fixing ppc for DaveM new stuff, I found a couple of things
that look strange (not directly related to the patch though)

 - dma_is_consistent(dma_addr_t address) : Did somebody actually expect
anything useful out of this function ? AFAIK, it makes no sense. There
is simply no way an arch like ppc that use per-page cache-inhibit
mappings to do consistent memory will be able to tell you if a given
_DMA_ address is consistent... that makes no sense.

 - dma_cache_sync(): What is that function supposed to do ? It's a
duplicate of the other sync() functions and David didn't even bother
turning it into _for_device/for_cpu... which is fine since it doesn't
even takes a struct device argument.

I vote for removing the 2 functions above. I suspect something using
them is broken anyway.

Ben.