Fix backtraces from ddb for powerpc, If addr is not specified, it will start using the ddb_regs. If the address is specififed, start from the address.
Fix backtraces from ddb for powerpc, If addr is not specified, it will
start using the ddb_regs. If the address is specififed, start from the
address.

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars