doc: Documentation/DMA-attributes.txt fix typo

Fix some typos in Documentation/DMA-attributes.txt.

Signed-off-by: Xishi Qiu <[e-mail]>
Acked-by: Rob Landley <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

Documentation/DMA-attributes.txt

···
 strictly order DMA from a device across all intervening busses and
 bridges.  This barrier is not specific to a particular type of
 interconnect, it applies to the system as a whole, and so its
-implementation must account for the idiosyncracies of the system all
+implementation must account for the idiosyncrasies of the system all
 the way from the DMA device to memory.
 
 As an example of a situation where DMA_ATTR_WRITE_BARRIER would be
···
 Buffers allocated with this attribute can be only passed to user space
 by calling dma_mmap_attrs(). By using this API, you are guaranteeing
 that you won't dereference the pointer returned by dma_alloc_attr(). You
-can threat it as a cookie that must be passed to dma_mmap_attrs() and
+can treat it as a cookie that must be passed to dma_mmap_attrs() and
 dma_free_attrs(). Make sure that both of these also get this attribute
 set on each call.
 
···
 (usually it means that the cache has been flushed or invalidated
 depending on the dma direction). However, next calls to
 dma_map_{single,page,sg}() for other devices will perform exactly the
-same sychronization operation on the CPU cache. CPU cache sychronization
+same synchronization operation on the CPU cache. CPU cache synchronization
 might be a time consuming operation, especially if the buffers are
 large, so it is highly recommended to avoid it if possible.
 DMA_ATTR_SKIP_CPU_SYNC allows platform code to skip synchronization of