crypto: ansi_cprng - Move FIPS functions under CONFIG_CRYPTO_FIPS

fips_cprng_get_random and fips_cprng_reset is used only by
CONFIG_CRYPTO_FIPS. This also fixes compilation warnings:

 crypto/ansi_cprng.c:360: warning: ‘fips_cprng_get_random’ defined but not used
 crypto/ansi_cprng.c:393: warning: ‘fips_cprng_reset’ defined but not used

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>