Documentation: remove duplicated words

Remove many duplicated words under Documentation/ and do other small
cleanups.

Examples:
        "and and" --> "and"
        "in in" --> "in"
        "the the" --> "the"
        "the the" --> "to the"
        ...

Signed-off-by: Paolo Ornati <ornati@fastwebnet.it>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
diff --git a/Documentation/DMA-mapping.txt b/Documentation/DMA-mapping.txt
index 1d8dccf..028614c 100644
--- a/Documentation/DMA-mapping.txt
+++ b/Documentation/DMA-mapping.txt
@@ -107,7 +107,7 @@
 
 	int pci_set_dma_mask(struct pci_dev *pdev, u64 device_mask);
 
-The query for consistent allocations is performed via a a call to
+The query for consistent allocations is performed via a call to
 pci_set_consistent_dma_mask():
 
 	int pci_set_consistent_dma_mask(struct pci_dev *pdev, u64 device_mask);