bmips: fix missing NVMEM subsystem
MAC address retrieval was switched to more generic upstream (5.13) NVMEM
based solution in commit 32adbfc789f6 ("bmips: convert mtd-mac-address
to nvmem implementation"), but NVMEM subsystem wasn't enabled in the
kernel, so fix it now.
References: https://github.com/openwrt/openwrt/pull/4041#issuecomment-883322801
Fixes: 32adbfc789f6 ("bmips: convert mtd-mac-address to nvmem implementation")
Signed-off-by: Petr Štetiar <[email protected]>
Petr Štetiar