crypto: stm32/hash - Use existing busy poll function

When exporting state we are waiting indefinitely in the same
was as the ordinary stm32_hash_wait_busy() poll-for-completion
function but without a timeout, which means we could hang in
an eternal loop. Fix this by waiting for completion like the
rest of the code.
Acked-by: Lionel Debieve <lionel.debieve@foss.st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/stm32/stm32-hash.c

@@ -960,11 +960,13 @@ static int stm32_hash_export(struct ahash_request *req, void *out)
 	struct stm32_hash_dev *hdev = stm32_hash_find_dev(ctx);
 	u32 *preg;
 	unsigned int i;
+	int ret;
 
 	pm_runtime_get_sync(hdev->dev);
 
-	while ((stm32_hash_read(hdev, HASH_SR) & HASH_SR_BUSY))
-		cpu_relax();
+	ret = stm32_hash_wait_busy(hdev);
+	if (ret)
+		return ret;
 
 	rctx->hw_context = kmalloc_array(3 + HASH_CSR_REGISTER_NUMBER,
 					 sizeof(u32),