Add parenthesis around all packet size definitions when they contain calculations

For example:

#define EIP_OBJECT_CIP_SERVICE_CNF_SIZE     (sizeof(EIP_OBJECT_CIP_SERVICE_CNF_T)) - EIP_OBJECT_MAX_PACKET_LEN

Should be:

#define EIP_OBJECT_CIP_SERVICE_CNF_SIZE     ((sizeof(EIP_OBJECT_CIP_SERVICE_CNF_T)) - EIP_OBJECT_MAX_PACKET_LEN)

Because otherwise, a customer who writes an expression like:

int ulDataLen = ptCnf->tHead.ulLen - EIP_OBJECT_CIP_SERVICE_CNF_SIZE;

Runs into a really nasty underflow.