realtek: Fix nvmem support for ethernet device

realtek: Fix nvmem support for ethernet device

The function of_get_mac_address is not taking care of evaluation the nvmem
address before trying to read out the mac-address properties. The driver
must check whether the return code is -EPROBE_DEFER and stop the probing
process in that case. If the nvmem-cell related driver code finished, the
probe can be redone ad the correct mac-address will appear for the device.

Signed-off-by: Harshal Gohel <[email protected]>
Signed-off-by: Sharadanand Karanjkar <[email protected]>
Link: https://github.com/openwrt/openwrt/pull/19362
Signed-off-by: Hauke Mehrtens <[email protected]>