net: yaip: Add net_send_data() that sends data to network

This function is not meant to be used by applications as it
requires that the IP headers etc. are already in place.

Change-Id: I9099671111a029cdf630d131d7af09b147486f64
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>