udf: Remove useless check in udf_adinicb_write_begin()

As Al properly points out, len is guaranteed to be smaller than
PAGE_SIZE when we reach udf_adinicb_write_begin() as otherwise we would
have converted the file to the normal format.
Reported-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/udf/file.c

@@ -94,7 +94,7 @@ static int udf_adinicb_write_begin(struct file *file,
 		return -ENOMEM;
 	*pagep = page;
 
-	if (!PageUptodate(page) && len != PAGE_SIZE)
+	if (!PageUptodate(page))
 		__udf_adinicb_readpage(page);
 	return 0;
 }