board: ge: bx50v3: Enable DM for PCI and ethernet

board: ge: bx50v3: Enable DM for PCI and ethernet

DM for PCI pulls DM for ethernet that also needs other changes described
below to build u-boot and keep existing functionality - ability to update
MAC addresses of FEC ethernet adapter and I210 adapter connected to the
Marvell switch.

- fec_mxc driver with DM needs PHYLIB;

- configuration items are moved from ge_bx50v3.h to ge_bx50v3_defconfig;

- FEC is marked as eth0 because it is always present, so indices changed:
  I210 are still probed in the same order;

- board_eth_init() was used by legacy ethernet, setup for enet iomux and
  pcie is moved to the board_late_init();

- pci_init() is called from the board_late_init() to initiate PCI bus
  probing, so I210 devices are propagated to the device tree;

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@ge.com>
[Describe PHY reset in device tree]
Signed-off-by: Ian Ray <ian.ray@ge.com>
Signed-off-by: Robert Beckett <bob.beckett@collabora.com>