Merge patch series "net: tcp: improve tcp support in legacy stack"

Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu> says:

Legacy TCP stack is bad. Here are some of the known issues:
 * tcp packet from other connection can break a current one
 * tcp send sequence always starts from zero
 * bad tcp options processing
 * strange assumptions on packet size for selective acknowledge
 * tcp interface assumes one of the two scenarios:
     - data downloading from remote host to a board
     - request-response exchange with a small packets
   so it's not possible to upload large amount of data from the
   board to remote host.
 * wget test generate bad tcp stream, test should fail but it passes instead

This series of patches fixes all of the above issues.

The benefits:
 * A lot of bug was fixed
 * Better and more reliable TCP state machine
 * Tcp clients becomes smaller/simpler
 * Data uploading was fixed (now it's possible to transmit a huge amount of
   data from the board to remote host)

Modification was verified with
 * firmware downloading via u-boot wget command
 * fastboot over tcp

Link: https://lore.kernel.org/r/20241114033643.623355-1-mikhail.kshevetskiy@iopsys.eu