net: phy: mscc: take into account the 1588 block in MACsec init

This patch takes in account the use of the 1588 block in the MACsec
initialization, as a conditional configuration has to be done (when the
1588 block is used).

Signed-off-by: Antoine Tenart <antoine.tenart@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>