ocfs2/cluster: neaten a member of o2net_msg_handler

ocfs2/cluster: neaten a member of o2net_msg_handler

It's odd that o2net_msg_handler::nh_func_data is declared as type
o2net_msg_handler_func*.  So neaten it.

Link: http://lkml.kernel.org/r/63ADC13FD55D6546B7DECE290D39E373F1F554DA@H3CMLB14-EX.srv.huawei-3com.com
Signed-off-by: Changwei Ge <[email protected]>
Reviewed-by: Joseph Qi <[email protected]>
Reviewed-by: Alex Chen <[email protected]>
Cc: Mark Fasheh <[email protected]>
Cc: Joel Becker <[email protected]>
Cc: Junxiao Bi <[email protected]>
Cc: Changwei Ge <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>