common/mlx5: share kernel interface name getter

common/mlx5: share kernel interface name getter

Some configuration of the mlx5 port are done by the kernel net device
associated to the IB device represents the PCI device.

The DPDK mlx5 driver uses Linux system calls, for example ioctl, in
order to configure per port configurations requested by the DPDK user.

One of the basic knowledges required to access the correct kernel net
device is its name.

Move function to get interface name from IB device path to the common
library.

Signed-off-by: Matan Azrad <matan@mellanox.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>