random32: Restore __latent_entropy attribute on net_rand_state

Commit f227e3ec ("random32: update the net random state on interrupt
and activity") broke compilation and was temporarily fixed by Linus in
83bdc727 ("random32: remove net_rand_state from the latent entropy
gcc plugin") by entirely moving net_rand_state out of the things handled
by the latent_entropy GCC plugin.

From what I understand when reading the plugin code, using the
__latent_entropy attribute on a declaration was the wrong part and
simply keeping the __latent_entropy attribute on the variable definition
was the correct fix.

Fixes: 83bdc727 ("random32: remove net_rand_state from the latent entropy gcc plugin")
Acked-by: NWilly Tarreau <w@1wt.eu>
Cc: Emese Revfy <re.emese@gmail.com>
Signed-off-by: NThibaut Sautereau <thibaut.sautereau@ssi.gouv.fr>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

lib/random32.c

@@ -49,7 +49,7 @@ static inline void prandom_state_selftest(void)
 }
 #endif
 
-DEFINE_PER_CPU(struct rnd_state, net_rand_state);
+DEFINE_PER_CPU(struct rnd_state, net_rand_state)  __latent_entropy;
 
 /**
  *	prandom_u32_state - seeded pseudo-random number generator.