selftests: fib_tests: Add test cases for IPv4/IPv6 FIB

Add test cases to check that IPv4 and IPv6 react to a netdev being
unregistered as expected.

Signed-off-by: Ido Schimmel <[email protected]>
Acked-by: David Ahern <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
2 files changed