crypto: ansi_cprng - Remove unused ansi_cprng algorithm

Remove ansi_cprng, since it's obsolete and unused, as confirmed at
https://lore.kernel.org/r/aQxpnckYMgAAOLpZ@gondor.apana.org.au/

This was originally added in 2008, apparently as a FIPS approved random
number generator.  Whether this has ever belonged upstream is
questionable.  Either way, ansi_cprng is no longer usable for this
purpose, since it's been superseded by the more modern algorithms in
crypto/drbg.c, and FIPS itself no longer allows it.  (NIST SP 800-131A
Rev 1 (2015) says that RNGs based on ANSI X9.31 will be disallowed after
2015.  NIST SP 800-131A Rev 2 (2019) confirms they are now disallowed.)

Therefore, there is no reason to keep it around.

Suggested-by: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Haotian Zhang <vulab@iscas.ac.cn>
Cc: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/Kconfig

@@ -25,7 +25,7 @@ menu "Crypto core or helper"
 
 config CRYPTO_FIPS
 	bool "FIPS 200 compliance"
-	depends on (CRYPTO_ANSI_CPRNG || CRYPTO_DRBG) && CRYPTO_SELFTESTS
+	depends on CRYPTO_DRBG && CRYPTO_SELFTESTS
 	depends on (MODULE_SIG || !MODULES)
 	help
 	  This option enables the fips boot option which is
@@ -1169,17 +1169,6 @@ endmenu
 
 menu "Random number generation"
 
-config CRYPTO_ANSI_CPRNG
-	tristate "ANSI PRNG (Pseudo Random Number Generator)"
-	select CRYPTO_AES
-	select CRYPTO_RNG
-	help
-	  Pseudo RNG (random number generator) (ANSI X9.31 Appendix A.2.4)
-
-	  This uses the AES cipher algorithm.
-
-	  Note that this option must be enabled if CRYPTO_FIPS is selected
-
 menuconfig CRYPTO_DRBG_MENU
 	tristate "NIST SP800-90A DRBG (Deterministic Random Bit Generator)"
 	help