/net/hsr: fix misspellings using codespell tool

A typo is found out by codespell tool in 111th line of hsr_debugfs.c:

$ codespell ./net/hsr/

net/hsr/hsr_debugfs.c:111: Debufs  ==> Debugfs

Fix typos found by codespell.

Signed-off-by: Xiong Zhenwu <xiong.zhenwu@zte.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>