net: phy: broadcom: Add support for BCM53128 internal PHYs

Add support for BCM53128 internal PHYs. These support interrupts as well as
statistics. Therefore, enable the Broadcom PHY driver for them.

Tested on BCM53128 switch using the mainline b53 DSA driver.

Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>