net: Add support for re-sending initial TCP SYN

If we are initiating a TCP connection, then make sure that
we try to re-send initial SYN packet (max 8 times) if it is lost.

Change-Id: I9fbc39bdaef3a535c480eb5433eb7ef3ad60d604
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>