tg3: Reset phy during bringup when using phylib

The driver puts the phy into low-power mode when it releases the device.
If the device were to be reacquired, the phy needs a reset to bring it
back to full powered operation.  This patch allows phylib-enabled
devices to reset the phy.

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>