sparc32: Move cache and TLB flushes over to method ops.
This eliminated most of the remaining users of btfixup. There are some complications because of the special cases we have for sun4d, leon, and some flavors of viking. It was found that there are no cases where a flush_page_for_dma method was not hooked up to something, so the "noflush" iommu methods were removed. Add some documentation to the viking_sun4d_smp_ops to describe exactly the hardware bug which causes us to need special TLB flushing on sun4d. Signed-off-by: David S. Miller <firstname.lastname@example.org>