Device driver for the Cypress CY7C637xx and CY7C640/1xx families of USB

Device driver for the Cypress CY7C637xx and CY7C640/1xx families of USB
to RS232 bridges, such as the one found in the DeLorme Earthmate USB GPS
receiver (which is the only device currently supported by this driver).

While other USB to serial drivers in the tree rely heavily on ucom, this
one is self-contained.  The reason for that is that ucom assumes that
the bridge uses bulk pipes for I/O, while the Cypress parts actually
register as human interface devices and use HID reports for configuration
and I/O.

The driver is not entirely complete: there is no support yet for flow
control, and output doesn't seem to work, though I don't know if that is
because of a bug in the code, or simply because the Earthmate is a read-
only device.