tg3: Enable EEE support for capable 10/100 devs

There are some devices in the 57765 ASIC rev that are EEE capable.
Unfortunately the EEE setup code only gets executed if the device is
gigabit capable.  This patch fixes the problem.

Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Reviewed-by: Michael Chan <mchan@broadcom.com>
Reviewed-by: Benjamin Li <benli@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>