ipmi-config/bmc-config issue warnings if Section cannot be met for motherboard instead of error

[chu11]

Use case: User can have single conf file for different motherboard types. E.g. if motherboard A allows max 2 users and motherboard B allows max 4 users, you cannot have a bmc-config with section "User4" in it for both motherboards. It will error on the one with max 2 users. Other potential variable length ones include platform event filtering and specific channel numbers.