Default baud rate to 115200 or suggest if error encountered

[lurch89]

I had a combination of devices (Arduino Uno UART onboard and WB2S chip) that required me to use 115200 instead of anything faster. It errored by beginning to read one block and then stalling. Once I rolled back to 115200 it worked great. It may be helpful for other users who are trying to flash on defaults to get a suggestion to try a slower speed.