This commit adds pciid to the LinuxNetwork fact object.

pciid is gathered if the symlink /sys/class/net/*/device exists.

Example [>>>> emphasis <<<<]:

$ readlink /sys/class/net/eth0/device
../../../0000:01:00.0

$ ansible localhost --ask-pass -i /tmp/hosts -m setup -a "filter=ansible_eth0"
SSH password:
localhost | success >> {
    "ansible_facts": {
        "ansible_eth0": {
            "active": false,
            "device": "eth0",
            "macaddress": "0c:d2:92:5d:6e:8e",
            "module": "alx",
            "mtu": 1500,
       >>>> "pciid": "0000:01:00.0", <<<<
            "promisc": true,
            "type": "ether"
        }
    },
    "changed": false
}