random: drop check for static_key_initialized

random: drop check for static_key_initialized

Commit e871abcda3b6 ("random: handle creditable entropy from atomic
process context") added the use of workqueues, which meant testing
whether the workqueue is valid, but it did not remove the existing check
of whether static keys have been initialized. This static key check is
unnecessary because workqueues are initialized long after it. And
semantically it doesn't make much sense either, because it's not really
directly calling a static key function in the condition.

Remove the now unnecessary check.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
[Jason: rewrite commit message with different explanation, rebase on
        random.git, and update code comment.]
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>