Adds the usb code that we got in ECE 385. It will not work now, and
parts that involve the timer are disabled. It does compile though, with
a few warnings.
The goal will be to add USB MSD support, which is not actually given to
us so I will have to do myself or find some other code to base it off
of.
Since the goal is to have the MAX3421E working, which uses multiple 8
bit transfers, we should support multiple 8 bit transfers instead of
trying to use 16 bit transfers.
When using spi_byte(), the device is automatically selected. After you
have made as many transfers as you want, you must deselect the device
with spi_deselect().
the SPI module reads and writes at the same time. If you don't want to
write a value, then write all zeros or whatever the device you are
communicating with wants.
