OpenPGP: Include private DO to filesystem at driver initialization.

In old implementation, the DOs which their access is restricted by
PIN (like DOs 0101 -> 0104) were excluded from the fake filesystem,
leading to that we cannot read their data later, even if we verified PIN.
PKCS15-OpenPGP: Declare DATA objects.

Begin to support read/write DATA object for PKCS-OpenPGP binding.
This object is used by TrueCrypt.
PKCS15-OpenPGP: Do not show empty DO in pkcs15 emu_init.
PKCS15-OpenPGP: Allow to store data to pkcs15 data object.

Only one DO is supported now.