random: handle latent entropy and command line from random_init()

Currently, start_kernel() adds latent entropy and the command line to
the entropy bool *after* the RNG has been initialized, deferring when
it's actually used by things like stack canaries until the next time
the pool is seeded. This surely is not intended.

Rather than splitting up which entropy gets added where and when between
start_kernel() and random_init(), just do everything in random_init(),
which should eliminate these kinds of bugs in the future.

While we're at it, rename the awkwardly titled "rand_initialize()" to
the more standard "random_init()" nomenclature.

Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

arch/openrisc/kernel/head.S

@@ -525,7 +525,7 @@ _start:
 	 * Start the TTCR as early as possible, so that the RNG can make use of
 	 * measurements of boot time from the earliest opportunity. Especially
 	 * important is that the TTCR does not return zero by the time we reach
-	 * rand_initialize().
+	 * random_init().
 	 */
 	l.movhi r3,hi(SPR_TTMR_CR)
 	l.mtspr r0,r3,SPR_TTMR