Documentation/DMA-API-HOWTO.txt: fix typo

Noted by Jesper

Cc: Jesper Juhl <jj@chaosbits.net>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Shuah Khan <shuah.khan@hp.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Documentation/DMA-API-HOWTO.txt

@@ -752,7 +752,7 @@ Example 1:
 		dma_unmap_single(dma_handle1);
 	map_error_handling1:
 
-Example 2: (if buffers are allocated a loop, unmap all mapped buffers when
+Example 2: (if buffers are allocated in a loop, unmap all mapped buffers when
 	    mapping error is detected in the middle)
 
 	dma_addr_t dma_addr;