ksmbd: Replace the ternary conditional operator with min()

It would be better to replace the traditional ternary conditional
operator with min() in compare_sids.

Signed-off-by: Lu Hongfei <luhongfei@vivo.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>