Documentation: move DMA-mapping.txt to Doc/PCI/

Move DMA-mapping.txt to Documentation/PCI/.

DMA-mapping.txt was supposed to be moved from Documentation/ to
Documentation/PCI/.  The 00-INDEX files in those two directories
were updated, along with a few other text files, but the file
itself somehow escaped being moved, so move it and update more
text files and source files with its new location.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
cc:	Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/media/videobuf-dma-sg.h b/include/media/videobuf-dma-sg.h
index 90edd22..dda47f0 100644
--- a/include/media/videobuf-dma-sg.h
+++ b/include/media/videobuf-dma-sg.h
@@ -49,7 +49,7 @@
  *	does memory allocation too using vmalloc_32().
  *
  * videobuf_dma_*()
- *	see Documentation/DMA-mapping.txt, these functions to
+ *	see Documentation/PCI/PCI-DMA-mapping.txt, these functions to
  *	basically the same.  The map function does also build a
  *	scatterlist for the buffer (and unmap frees it ...)
  *