nfp doing its own pci_read_config

[Stephen Hemminger <stephen@networkplumber.org>]

Why is Netronome driver using its own version of existing rte_pci_read_config?
And hard coding magic numbers for offsets.

This shows up as Coverity error
________________________________________________________________________________________________________
*** CID 277243:  Error handling issues  (CHECKED_RETURN)
/drivers/net/nfp/nfpcore/nfp_cpp_pcie_ops.c: 684 in nfp6000_set_interface()
678     		 desc->busdev);
679     
680     	fp = open(tmp_str, O_RDONLY);
681     	if (!fp)
682     		return -1;
683     
>>>     CID 277243:  Error handling issues  (CHECKED_RETURN)
>>>     Calling "lseek(fp, 340L, 0)" without checking return value. This library function may fail and return an error code.  
684     	lseek(fp, 0x154, SEEK_SET);
685     
686     	if (read(fp, &tmp, sizeof(tmp)) != sizeof(tmp)) {
687     		printf("error reading config file for interface\n");
688     		return -1;
689  


static int
nfp6000_set_model(struct nfp_pcie_user *desc, struct nfp_cpp *cpp)
{
	char tmp_str[80];
	uint32_t tmp;
	int fp;

	snprintf(tmp_str, sizeof(tmp_str), "%s/%s/config", PCI_DEVICES,
		 desc->busdev);

	fp = open(tmp_str, O_RDONLY);
	if (!fp)
		return -1;

	lseek(fp, 0x2e, SEEK_SET);

	if (read(fp, &tmp, sizeof(tmp)) != sizeof(tmp)) {
		printf("Error reading config file for model\n");
		return -1;
	}

	tmp = tmp << 16;