Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/drivers/media/video/au0828/au0828-video.c b/drivers/media/video/au0828/au0828-video.c
index 6ad83a1..c03eb29 100644
--- a/drivers/media/video/au0828/au0828-video.c
+++ b/drivers/media/video/au0828/au0828-video.c
@@ -502,7 +502,7 @@
 
 	/* Get the next buffer */
 	*buf = list_entry(dma_q->active.next, struct au0828_buffer, vb.queue);
-	/* Cleans up buffer - Usefull for testing for frame/URB loss */
+	/* Cleans up buffer - Useful for testing for frame/URB loss */
 	outp = videobuf_to_vmalloc(&(*buf)->vb);
 	memset(outp, 0x00, (*buf)->vb.size);