Commit b41f26845a ('Add support for
offloading key management operations to the driver') used incorrect
variable for determining the KCK length. This does not get triggered in
normal use cases since KCK and KEK are always included and of the same
length (in currently supported key management cases). Anyway, this needs
to be fixed to check the correct attribute. (CID 74491)
Signed-off-by: Jouni Malinen <j@w1.fi>