crypto: prefix module autoloading with "crypto-"

This prefixes all crypto module loading with "crypto-" so we never run
the risk of exposing module auto-loading to userspace via a crypto API,
as demonstrated by Mathias Krause:

https://lkml.org/lkml/2013/3/4/70

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/ansi_cprng.c b/crypto/ansi_cprng.c
index 666f196..b4485a1 100644
--- a/crypto/ansi_cprng.c
+++ b/crypto/ansi_cprng.c
@@ -476,4 +476,4 @@
 MODULE_PARM_DESC(dbg, "Boolean to enable debugging (0/1 == off/on)");
 module_init(prng_mod_init);
 module_exit(prng_mod_fini);
-MODULE_ALIAS("stdrng");
+MODULE_ALIAS_CRYPTO("stdrng");