ksmbd: Remove unused fields from ksmbd_file struct definition

These fields are remnants of the not upstreamed SMB1 code.

Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Marios Makassikis <mmakassikis@freebox.fr>
Signed-off-by: Steve French <stfrench@microsoft.com>