net: tests: Add IPv4 address unit tests

These tests will check that caller is able to set IPv4 address
to a network interface and check if an address is one of the
assigned to a network interface.

Change-Id: I8aa748c40fbc02eef50ccf76d10a0057ef29021b
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>