There is no reason why code handling MAC-address properties of
"ocotp0" and code fetching this information to pass it along to
networking subsystem couldn't share majority of their code. Convert
the driver to do that.

Cc: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Tested-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>