On some newer platforms the device ignore the configure request to
disable ZLP, causing the Firehose program request to stall, when the
device is waiting for a ZLP to end a transfer.

Mitigate this by circumventing the qcserial driver and drive the USB
traffic directly using USBFS. The tool will attempt to detach qcserial
from the device, in case it's already attached, so no changes are needed
in the kernel or system configuration.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>