Fix sparse warnings:

fs/cifs/smb2pdu.c:3200:1: warning: symbol 'SMB2_notify_init' was not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>