random: delete code to pull data into pools

There is no pool that pulls, so it was just dead code.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/4a05fe0c7a5c831389ef4aea51d24528ac8682c7.1577088521.git.luto@kernel.org


Signed-off-by: Theodore Ts'o <tytso@mit.edu>