net: phy: broadcom: Utilize appropriate suspend for BCM54810/11

Since we enable APD and DLL/RXC/TXC disable we need to use
bcm54xx_suspend() in order not to do a read/modify/write of the BMCR
register which is incompatible with the desired settings.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>