MAINTAINERS: remove Hyunchul Lee from ksmbd maintainers

I don't have the necessary time to maintain
the ksmbd code. So remove myself from maintainers
of ksmbd.

Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com>
Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>