eeprom: Suck the ifdef into eeprom_init()

Just suck the ugly ifdef around eeprom_init() call into eeprom_init()
function itself. This puts all of the ifdef mess into one place.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>
Cc: Heiko Schocher <hs@denx.de>
Reviewed-by: Heiko Schocher <hs@denx.de>