Add IDISK_NAME and INIC_NAME constants

Declare IDISK_NAME and INIC_NAME constants and add them to the
IDISK_PARAMS_TYPE and INIC_PARAMS_TYPE.

Signed-off-by: Christos Stavrakakis <cstavr@grnet.gr>
Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
Reviewed-by: Helga Velroyen <helgav@google.com>