kill the 4th argument of __generic_file_aio_write()

It's always equal to &iocb->ki_pos, where iocb is the value of the 1st
argument.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 1a50739..d564bcf 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -146,7 +146,7 @@
 			overwrite = 1;
 	}
 
-	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
+	ret = __generic_file_aio_write(iocb, iov, nr_segs);
 	mutex_unlock(&inode->i_mutex);
 
 	if (ret > 0) {