Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/include/video/sisfb.h b/include/video/sisfb.h
index fdd74f1..6dc5df9 100644
--- a/include/video/sisfb.h
+++ b/include/video/sisfb.h
@@ -151,7 +151,7 @@
 	__u32  sisfb_result[4];
 };
 
-/* Addtional IOCTLs for communication sisfb <> X driver                */
+/* Additional IOCTLs for communication sisfb <> X driver                */
 /* If changing this, vgatypes.h must also be changed (for X driver)    */
 
 /* ioctl for identifying and giving some info (esp. memory heap start) */