Do not collect InfiniBand counters for Broadcom RoCE NICs

[oneoneonepig]

Broadcom RoCE NICs (bnxt_re#) does not have the counter metrics exposed in /sys/class/infiniband/<device>/ports/<port-num>/counter.

$ strace -e trace=open,openat node_exporter --log.level=debug
...
1270794 openat(AT_FDCWD, "/sys/class/infiniband/bnxt_re0/ports/1/counters", O_RDONLY|O_CLOEXEC) = -1 ENOENT (No such file or directory)
...

$ ls /sys/class/infiniband/bnxt_re0/ports/1/counters
ls: cannot access '/sys/class/infiniband/bnxt_re0/ports/1/counters': No such file or directory

This will cause Node Exporter to never collect any InfiniBand metrics since it always return with error ENOENT

[SuperQ]

Thanks