sctp: remove macros sctp_local_bh_{disable|enable}

Redefined local_bh_{disable|enable} to sctp_local_bh_{disable|enable}
for user space friendly code which we haven't use in years, so removing them.

Signed-off-by: Wang Weidong <wangweidong1@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>