sha512: free SHA-512/384 W cache with its allocated memory type

With WOLFSSL_SMALL_STACK_CACHE, wc_Sha512Free and wc_Sha384Free freed the
cached W buffer as DYNAMIC_TYPE_TMP_BUFFER, but it is allocated as
DYNAMIC_TYPE_DIGEST in InitSha512_Family/InitSha384 and the Copy functions
(the in-Init error cleanup already frees it as DYNAMIC_TYPE_DIGEST).

The mismatch is flagged by the memusage test (DHE_RSA TLS1.2 reports
Errors: 2) and matters for type-bucketed static memory pools. SHA-256/224
already use DYNAMIC_TYPE_DIGEST consistently. Free W as DYNAMIC_TYPE_DIGEST.

Author: julek-wolfssl

wolfcrypt/src/sha512.c

@@ -2306,7 +2306,7 @@ void wc_Sha512Free(wc_Sha512* sha512)
 #ifdef WOLFSSL_SMALL_STACK_CACHE
     if (sha512->W != NULL) {
         ForceZero(sha512->W, (sizeof(word64) * 16) + WC_SHA512_BLOCK_SIZE);
-        XFREE(sha512->W, sha512->heap, DYNAMIC_TYPE_TMP_BUFFER);
+        XFREE(sha512->W, sha512->heap, DYNAMIC_TYPE_DIGEST);
         sha512->W = NULL;
     }
 #endif
@@ -2779,7 +2779,7 @@ void wc_Sha384Free(wc_Sha384* sha384)
 #ifdef WOLFSSL_SMALL_STACK_CACHE
     if (sha384->W != NULL) {
         ForceZero(sha384->W, (sizeof(word64) * 16) + WC_SHA512_BLOCK_SIZE);
-        XFREE(sha384->W, sha384->heap, DYNAMIC_TYPE_TMP_BUFFER);
+        XFREE(sha384->W, sha384->heap, DYNAMIC_TYPE_DIGEST);
         sha384->W = NULL;
     }
 #endif