crypto: atmel - Check for clk_prepare_enable() return value

clk_prepare_enable() can fail so add a check for this and
return the error code if it fails.

Signed-off-by: LABBE Corentin <clabbe.montjoie@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/drivers/crypto/atmel-aes.c b/drivers/crypto/atmel-aes.c
index 0f9a9dc..de8f5da 100644
--- a/drivers/crypto/atmel-aes.c
+++ b/drivers/crypto/atmel-aes.c
@@ -260,7 +260,11 @@
 
 static int atmel_aes_hw_init(struct atmel_aes_dev *dd)
 {
-	clk_prepare_enable(dd->iclk);
+	int err;
+
+	err = clk_prepare_enable(dd->iclk);
+	if (err)
+		return err;
 
 	if (!(dd->flags & AES_FLAGS_INIT)) {
 		atmel_aes_write(dd, AES_CR, AES_CR_SWRST);