raw-posix: Typo fix

Signed-off-by: NFrediano Ziglio <freddy77@gmail.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/raw-posix.c

@@ -587,7 +587,7 @@ static BlockDriverAIOCB *raw_aio_submit(BlockDriverState *bs,
 
     /*
      * If O_DIRECT is used the buffer needs to be aligned on a sector
-     * boundary.  Check if this is the case or telll the low-level
+     * boundary.  Check if this is the case or tell the low-level
      * driver that it needs to copy the buffer.
      */
     if (s->aligned_buf) {