init: Update to new uknetdev einfo field names

init: Update to new uknetdev einfo field names

[PR#1211](https://github.com/unikraft/unikraft/pull/1211) in Unikraft core
changes `uk_netdev_einfo_get()` to return C-strings only and removed the
`_STR` name suffix of the fields that we are using to setup a statically
assigned IPv4 address.

Signed-off-by: Simon Kuenzer <simon@unikraft.io>
Reviewed-by: Stefan Jumarea <stefanjumarea02@gmail.com>
Approved-by: Razvan Deaconescu <razvand@unikraft.io>
GitHub-Closes: #42