tcp: Bug fix in initialization of receive window.

tcp: Bug fix in initialization of receive window.

[ Upstream commit b1afde60f2b9ee8444fba4e012dc99a3b28d224d ]

The bug has to do with boundary checks on the initial receive window.
If the initial receive window falls between init_cwnd and the
receive window specified by the user, the initial window is incorrectly
brought down to init_cwnd. The correct behavior is to allow it to
remain unchanged.

Signed-off-by: Nandita Dukkipati <nanditad@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>