crypto: drbg - Fix unused value warning in drbg_healthcheck_sanity()

Coverity warns uf an unused value:

CID 44865 (#2 of 2): Unused value (UNUSED_VALUE)
assigned_value: Assigning value -14 to ret here, but that stored value is
overwritten before it can be used.
2006        int ret = -EFAULT;
...
value_overwrite: Overwriting previous write to ret with value from drbg_seed(drbg, &addtl, false).
2052        ret = drbg_seed(drbg, &addtl, false);

Fix this by removing the variable initializer.

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-crypto@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/drbg.c

@@ -2003,7 +2003,7 @@ static inline int __init drbg_healthcheck_sanity(void)
 #define OUTBUFLEN 16
 	unsigned char buf[OUTBUFLEN];
 	struct drbg_state *drbg = NULL;
-	int ret = -EFAULT;
+	int ret;
 	int rc = -EFAULT;
 	bool pr = false;
 	int coreref = 0;