Draft: samsung-janice: Switch to general firmware package

This PR switches the firmware package to the generic platform one firmware-samsung-u8500 for Samsung Janice. Marked as draft because I'm still testing the changes.

Unfortunately Wifi and Bluetooth doesn't show up. Not in bluetoothctl nor in ip a. dmesg has no output regarding Broadcom firmware or devices. Not sure how to fix this 😞 @linusw