i2c: Clearly mark ACPI drivers as such

Now that we have ACPI-based SMBus controller drivers, and we will start
telling users to use them instead of native drivers when I/O resources
conflict, I think it would be good to clearly mark ACPI drivers as such
in Kconfig.

This is exactly the same as we just did for hwmon drivers.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Crane Cai <crane.cai@amd.com>