net: yaip: Add capabilities flag to net_if API

The network device driver can specify what kind of functionality
it supports. Currently there exists one flag that can be used
in ethernet devices that tells that ARP should be enabled.

Change-Id: Ieaaefcfc7cdd65f44190248f507ac3cb512a323e
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>