ksmbd: validate handle for create or get object id

ksmbd: validate handle for create or get object id

FSCTL_CREATE_OR_GET_OBJECT_ID returned a dummy successful response without
checking whether the request handle was valid. That let an invalid related
compound handle succeed in smb2.compound.related5, although the client
expected STATUS_FILE_CLOSED.

Look up the file handle before building the object id response and fail
with STATUS_FILE_CLOSED when the handle is invalid or already closed.

Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>