dma-buf: Rename dma-ops to prevent conflict with kunmap_atomic macro

Seeing the kunmap_atomic dma_buf_ops share the same name with a macro
in highmem.h, the former can be aliased if any dma-buf user includes
that header.

I'm personally trying to include highmem.h inside scatterlist.h and this
breaks the dma-buf code proper.

Christoph Hellwig suggested [1] renaming it and pushing this patch ASAP.

To maintain consistency I've renamed all four of kmap* and kunmap* to be
map* and unmap*. (Even though only kmap_atomic presently conflicts.)

[1] https://www.spinics.net/lists/target-devel/msg15070.html



Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1492630570-879-1-git-send-email-logang@deltatee.com