tcp: remove unused ICSK_TIME_EARLY_RETRANS

Since the early retransmit has been removed by
commit bec41a11

 ("tcp: remove early retransmit"),
we also remove the unused ICSK_TIME_EARLY_RETRANS macro.

Signed-off-by: Pengcheng Yang <yangpc@wangsu.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/1611239473-27304-1-git-send-email-yangpc@wangsu.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>