This reverts commit 0613d3e3561a82fffa36594647ef916b19bc912b.
The value of CFG_TUD_CDC_EP_BUFSIZE should match the endpoint size,
otherwise data may stay in the lower layers of the USB stack (and not
passed up to the higher layers) until a total of CFG_TUD_CDC_EP_BUFSIZE
bytes have been received, which may not happen for a long time.
Fixes issue #11253.
Signed-off-by: Damien George <damien@micropython.org>