bridge: correct the comment for file br_sysfs_br.c

br_sysfs_if.c is for sysfs attributes of bridge ports, while br_sysfs_br.c
is for sysfs attributes of bridge itself. Correct the comment here.
Signed-off-by: NWang Sheng-Hui <shhuiw@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/bridge/br_sysfs_br.c

 /*
- *	Sysfs attributes of bridge ports
+ *	Sysfs attributes of bridge
  *	Linux ethernet bridge
  *
  *	Authors: