parsers: use proper conversion routine for PD option data types

parsers: use proper conversion routine for PD option data types

The generic_arg_to_opt() routine converted text input to protocol
decoder option values, but might have lost significant information.
Use a signed conversion routine for the int32 data, use a long long
routine for uint64 data. This shall unbreak negative values (like
UART packet separators), and improve compatibility with 32bit targets
(like for large sample numbers or high frequency values).