Revert random: Add hook to override device reads and getrandom(2)

The random system upstream is in a period of major rewrite. In the 5.18 merge window, it took a considerable amount of time to message this into the random.c rewrites. In the 5.19 merge window, rng->extrng_read(buf, count); does not even compile, with buf and count undefined. I am just reverting the whole thing, and it can be added back when Herbert has time or motivation to do so.

Signed-off-by: Justin M. Forbes jforbes@fedoraproject.org