[RAUC][SYSDATA] Extended custom bootloader script
The custom bootloader script has been extended. The set_primary_slot, get_boot_state and set_boot_state functions are now working.
Remarks:
- The fw_sysdata tool doesn't support separate boot fail counters. For this reason, if the state is queried or set for a slot other than the primary slot, the script exits with a non-zero return code.
- The boot_state is determined by evaluating the boot fail counter. If the counter is zero, good is returnd. Otherwise, bad is echoed.
(cherry picked from commit 7f6cef9b)