The default rx buffer water marks for XOFF/XON are for 1500 MTU.  At
larger MTUs, these water marks need to be adjusted for effective
flow control.
Signed-off-by: NMichael Chan <mchan@broadcom.com>
Signed-off-by: NMatt Carlson <mcarlson@broadcom.com>
Signed-off-by: NBenjamin Li <benli@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>