UPSTREAM: tcp: define initial scaling factor value as a macro

So that other users could access it. Notably MPTCP will use
it in the next patch.

No functional change intended.

Bug: 341320179
Change-Id: Ia4d8e3854abf87af1e7e9c2fbf056b7e84d32487
Acked-by: Matthieu Baerts <matttbe@kernel.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Mat Martineau <martineau@kernel.org>
Link: https://lore.kernel.org/r/20231023-send-net-next-20231023-2-v1-4-9dc60939d371@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit 849ee75a)
Signed-off-by: Subash Abhinov Kasiviswanathan <quic_subashab@quicinc.com>