net: zynq: Add support for different PHY interface types

net: zynq: Add support for different PHY interface types

MII is setup by default for all cases. The most of boards are using
RGMII but PHY drivers are not doing any specific setting that's why MII
setting was working fine. With TI DP83867 is necessary to setup
paramaters based on interface type.

Use one setting per board for it which is something what will be removed
when driver is moved to DM.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>