net/tcp: simplify tcp header filling code

This patch:
 * remove useless code,
 * use a special function for pretty printing of tcp flags,
 * simplify the code

The behavior should not be changed.

Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
Reviewed-by: Simon Glass <sjg@chromium.org>
1 file changed