libqiprog: Don't hardcode CONFIG_DRIVER_USB_MASTER

Move the CONFIG_DRIVER_USB_MASTER to a compiler argument, and don't define
it in software. This allows the same code to be used in QiProg devices with
less effort.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
libqiprog: Remove unused 'init' member in drivers

A driver should not need to initialize itself in order to perform its
duties. A device's initialization should be handled in .dev_open, if needed
We can bring .init back later if it makes sense, but for now, take it out.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
doc: "Pretty-ize" protocol description in markdown format

The old plaintext form was slightly readable in a text editor, and
completely harsh on the eyes in a browser. I find the new markdown form
easier to read in both a browser and text editor.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
libqiprog Add members for all functions in driver struct

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
libqiprog: Implement qiprog_set_bus

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
qiprog: Call qiprog_set_bus on the first discovered device

Set the device to the LPC bus. This is meant as a short-term solution while
the VultureProg firmware is being developed and tested.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
libqiprog: Add missing "return" statements in core.c

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>