configs: amlogic: Disable CONFIG_NET_RANDOM_ETHADDR when unnecessary

configs: amlogic: Disable CONFIG_NET_RANDOM_ETHADDR when unnecessary

On Meson GXL, GXM, AXG, G12A, G12B & SM1 SoCs, we can generate an unique
MAC address if none valid found in the eFuses storage.

Only the GXBB based boards doesn't have a fallback way to generate an
unique MAC address, so we rely on CONFIG_NET_RANDOM_ETHADDR to have
a valid one.

An exception is the Radxa Zero board who doesn't have Ethernet on board
so depends on an (or multiple) eventual USB adapters, so leaving the
CONFIG_NET_RANDOM_ETHADDR configs seems safer.

Suggested-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Vyacheslav Bocharov <adeep@lexina.in>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://lore.kernel.org/r/20211122110710.1038893-1-narmstrong@baylibre.com