net: phy: broadcom: Do not modify LED configuration for SFP module PHYs

bcm54xx_config_init was modifying the PHY LED configuration to enable link
and activity indications. However, some SFP modules (such as Bel-Fuse
SFP-1GBT-06) have no LEDs but use the LED outputs to control the SFP LOS
signal, and modifying the LED settings will cause the LOS output to
malfunction. Skip this configuration for PHYs which are bound to an SFP
bus.

Signed-off-by: Robert Hancock <robert.hancock@calian.com>
Signed-off-by: David S. Miller <davem@davemloft.net>