Since now variable 'flags' is not used anymore, remove it as well.
Otherwise there is a compile warning "unused variable 'flags'".

Fixes: e1843f01 ("NFSv4.1: Again fix a race where CB_NOTIFY_LOCK fails to wake a waiter")
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>