i2c: smbus: remove i801 assumptions from SPD probing

i2c: smbus: remove i801 assumptions from SPD probing

The check and warning are very specific to the SPD usage of the i801
driver. That was fine as long as i801 was the only caller of
i2c_register_spd(). Now that piix4 will be added as another user of that
function, the check and warning are not accurate anymore.
Instead of introducing a more complicated calling protocol only to print
a warning, drop the warning.
Even in cases where not all slots can be probed,
then at least probe the 8 slots that can be.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>