crypto: drbg - remove check for uninitialized DRBG handle

The drbg_healthcheck() contained a test to call the DRBG with an
uninitialized DRBG cipher handle. As this is an inappropriate use of the
kernel crypto API to try to generate random numbers before
initialization, checks verifying for an initialized DRBG have been
removed in previous patches.

Now, the drbg_healthcheck test must also be removed.

Changes V2: Added patch marker to email subject line.

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