Revert "USB: serial: ch341: fix character loss at high transfer rates"

Revert "USB: serial: ch341: fix character loss at high transfer rates"

This reverts commit 3c18e9baee0ef97510dcda78c82285f52626764b.

These devices do not appear to send a zero-length packet when the
transfer size is a multiple of the bulk-endpoint max-packet size. This
means that incoming data may not be processed by the driver until a
short packet is received or the receive buffer is full.

Revert back to using endpoint-sized receive buffers to avoid stalled
reads.

Reported-by: Paul Größel <pb.g@gmx.de>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=214131
Fixes: 3c18e9baee0e ("USB: serial: ch341: fix character loss at high transfer rates")
Cc: stable@vger.kernel.org
Cc: Willy Tarreau <w@1wt.eu>
Link: https://lore.kernel.org/r/20210824121926.19311-1-johan@kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>