Revert "bmips: huawei-hg556a-c: use nvmem for wifi eeprom"

Revert "bmips: huawei-hg556a-c: use nvmem for wifi eeprom"

This reverts commit 72f43ac220616fbd2f9658b9b60a861e8565a998.

The NVMEM codepath does not perform automatic byte conversion. It can be
fixed but the upstream version is quite different from the local
mac80211 patch. Revert until mac80211 gets updated and the whole mess
can get squared away.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/22091
Signed-off-by: Robert Marko <robimarko@gmail.com>
(cherry picked from commit b270580deabb40fa7af702d35d32b1f9f80fd007)