net: asix: add read_mac function

net: asix: add read_mac function

Initial device MAC should be read while getting info about the
device, so it's wrong to only read it in asix_init().

Add a dedicated function to read the initial MAC, which is also
able to handle devices that have their initial MAC stored in
EEPROM. Call this function inasix_eth_get_info().

Signed-off-by: Lucas Stach <dev@lynxeye.de>
Reviewed-by: Marek Vasut <marex@denx.de>
Acked-by: Marek Vasut <marex@denx.de>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>