the bulk out buffer size to 16 bytes. The bulk out endpoint descriptor
reports 32 bytes, but if you use this value, data will get dropped.
Reviewed/approved by: scottl
This is based on the ubsa driver by Alexander Kabaev along with documentation
gleaned from the Linux mct_u232 driver. I've had this driver sitting in my
tree for almost 6 months, and several others have found it useful.