net: tcp: Print TCP trace in one line

Print TCP header information in one line as there is really no
need to use multiple lines. Also use debug level when printing
the header info so that it is only seen if debugging is activated.

Change-Id: I27f314ca060239545769dec07148897da3426436
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>