Address a bug in the DRBG tests where the reseeding wasn't properly

reinstantiating the DRBG.

Bug reported by Doug Gibbons.
Reviewed-by: NPaul Yang <yang.yang@baishancloud.com>
(Merged from https://github.com/openssl/openssl/pull/8184)

(cherry picked from commit b1522fa5ef676b7af0128eab3eee608af3416182)

test/drbgtest.c

@@ -420,7 +420,7 @@ static int error_check(DRBG_SELFTEST_DATA *td)
      */
 
     /* Test explicit reseed with too large additional input */
-    if (!init(drbg, td, &t)
+    if (!instantiate(drbg, td, &t)
             || RAND_DRBG_reseed(drbg, td->adin, drbg->max_adinlen + 1, 0) > 0)
         goto err;
 
@@ -431,7 +431,7 @@ static int error_check(DRBG_SELFTEST_DATA *td)
         goto err;
 
     /* Test explicit reseed with too much entropy */
-    if (!init(drbg, td, &t))
+    if (!instantiate(drbg, td, &t))
         goto err;
     t.entropylen = drbg->max_entropylen + 1;
     if (!TEST_int_le(RAND_DRBG_reseed(drbg, td->adin, td->adinlen, 0), 0)
@@ -439,7 +439,7 @@ static int error_check(DRBG_SELFTEST_DATA *td)
         goto err;
 
     /* Test explicit reseed with too little entropy */
-    if (!init(drbg, td, &t))
+    if (!instantiate(drbg, td, &t))
         goto err;
     t.entropylen = drbg->min_entropylen - 1;
     if (!TEST_int_le(RAND_DRBG_reseed(drbg, td->adin, td->adinlen, 0), 0)