Fix missing initializations on some error paths

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/suites/test_suite_ctr_drbg.function b/tests/suites/test_suite_ctr_drbg.function
index 7d81608..c689699 100644
--- a/tests/suites/test_suite_ctr_drbg.function
+++ b/tests/suites/test_suite_ctr_drbg.function
@@ -31,15 +31,13 @@
                                        data_t *result)
 {
     mbedtls_ctr_drbg_context ctx;
+    mbedtls_ctr_drbg_init(&ctx);
     unsigned char buf[64];
 
     size_t entropy_chunk_len = (size_t) entropy_len_arg;
-
     TEST_ASSERT(entropy_chunk_len <= sizeof(buf));
 
     test_offset_idx = 0;
-    mbedtls_ctr_drbg_init(&ctx);
-
     test_max_idx = entropy->len;
 
     /* CTR_DRBG_Instantiate(entropy[:entropy->len], nonce, perso, <ignored>)