Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/Documentation/video4linux/README.pvrusb2 b/Documentation/video4linux/README.pvrusb2
index a747200..2137b58 100644
--- a/Documentation/video4linux/README.pvrusb2
+++ b/Documentation/video4linux/README.pvrusb2
@@ -172,7 +172,7 @@
     to provide a streaming API usable by a read() system call style of
     I/O.  Right now this is the only layer on top of pvrusb2-io.[ch],
     however the underlying architecture here was intended to allow for
-    other styles of I/O to be implemented with additonal modules, like
+    other styles of I/O to be implemented with additional modules, like
     mmap()'ed buffers or something even more exotic.
 
   pvrusb2-main.c - This is the top level of the driver.  Module level