crypto: drbg - ignore jitterentropy errors if not in FIPS mode

A subsequent patch will make the jitterentropy RNG to unconditionally
report health test errors back to callers, independent of whether
fips_enabled is set or not. The DRBG needs access to a functional
jitterentropy instance only in FIPS mode (because it's the only SP800-90B
compliant entropy source as it currently stands). Thus, it is perfectly
fine for the DRBGs to obtain entropy from the jitterentropy source only
on a best effort basis if fips_enabled is off.

Make the DRBGs to ignore jitterentropy failures if fips_enabled is not set.

Signed-off-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>