Fixes gcc '-Wunused-but-set-variable' warning:

fs/cifs/sess.c: In function sess_auth_lanman:
fs/cifs/sess.c:910:8: warning: variable capabilities set but not used [-Wunused-but-set-variable]
Reported-by: NHulk Robot <hulkci@huawei.com>
Signed-off-by: Nzhengbin <zhengbin13@huawei.com>
Signed-off-by: NSteve French <stfrench@microsoft.com>