arm: socfpga: misc: Add proper ethernet initialization

arm: socfpga: misc: Add proper ethernet initialization

Add function to initialize the EMAC blocks upon board startup.
The preprocessor guards against building on SoCFPGA-VT and against
SPL build are not needed as those are handled implicitly via both
SPL framework and the socfpga_cyclone5.h config file, which will
not define CONFIG_DESIGNWARE_ETH if building for SoCFPGA-VT.

We cannot handle two EMAC ethernet blocks yet, therefore the ifdefs.
Once there is hardware using both EMAC blocks, this ifdef will have
to go.

Signed-off-by: Pavel Machek <[email protected]>
Signed-off-by: Marek Vasut <[email protected]>
Cc: Chin Liang See <[email protected]>
Cc: Dinh Nguyen <[email protected]>
Cc: Albert Aribaud <[email protected]>
Cc: Tom Rini <[email protected]>
Cc: Wolfgang Denk <[email protected]>
Cc: Pavel Machek <[email protected]>