Increased size of #defined CFG_TUD_CDC_EPSIZE

[DavePutz]

Issue #1639 Application exception output to serial (over USB) appears truncated due to buffering issue

Increased size of #defined CFG_TUD_CDC_EPSIZE to 128 from tinyusb default of 64.
Reproduced issue 80%+ of the time by running in REPL on CircuitPlayground Express:
>>> raise AttributeError('abcdefghij' * 12)

Note that there is certainly some timing/host driver issue involved, since running the same code when
connected to a Linux instance on the same system never reproduced the code.
I believe the issue is in function tud_cdc_n_write_flush() from lib/tinyusb/src/class/cdc/cdc_device.c:

uint16_t count = tu_fifo_read_n(&_cdcd_itf[itf].tx_ff, p_cdc->epin_buf, CFG_TUD_CDC_EPSIZE);

This limits the count of what is to be flushed to CFG_TUD_CDC_EPSIZE. When a buffer larger than that needs flushing it seems to not flush anything.

[tannewt]

Thanks for taking a look at this @DavePutz !

I'd rather not change this size. I think it's hiding the issue rather than fixing it.

Our code should be able to chop a larger buffer into multiple tinyusb calls here: https://github.com/adafruit/circuitpython/blob/master/supervisor/shared/serial.c#L60

Maybe TinyUSB is incorrectly reporting a count back?