Handle no-ack

[Tiwalun]

See documentation for e.g. DAP_transfer: https://arm-software.github.io/CMSIS_5/DAP/html/group__DAP__Transfer.html

Bit 2..0: ACK (Acknowledge) value:

1 = OK (for SWD protocol), OK or FAULT (for JTAG protocol),
2 = WAIT
4 = FAULT
7 = NO_ACK (no response from target)

That also matches the ARM Debug Interface spec, where protocol error is used for cases like a parity error or the stop bit being wrong.

This makes it possible for probe-rs to handle NoAck differently from protocol errors.

[korken89]

Nice fix, thanks!