This commit removes the HWProbes() function from the console and tty
packages and replaces it with a global ProbeFuncs slice which is fetched
by the hal package when the hardware autodetection code runs.
Each driver should provide an init() function that appends a probe function
to the global ProbeFuncs slice.
This approach allows us to support conditional compilation of drivers in
the future (e.g. using build tags)
