i2c: smbus: Prepare i2c_register_spd for usage on muxed segments

i2c: smbus: Prepare i2c_register_spd for usage on muxed segments

If this is an adapter on a muxed bus segment, assume that each segment
is connected to a subset of the (> 8) overall memory slots. In this
case let's probe the maximum of 8 slots, however stop if the number
of overall populated slots is reached.

If we're not on a muxed segment and the total number of slots is > 8,
then warn because then not all SPD eeproms can be addressed.
Presumably the bus is muxed, but the mux config is missing.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
[wsa: removed a superfluous printout]
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>