hwrng: atmel - use clk_disable_unprepare instead of clk_disable

Since clk_prepare_enable() is used to get trng->clk, we should
use clk_disable_unprepare() to release it for the error path.
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Acked-by: NNicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/atmel-rng.c

@@ -94,7 +94,7 @@ static int atmel_trng_probe(struct platform_device *pdev)
 	return 0;
 
 err_register:
-	clk_disable(trng->clk);
+	clk_disable_unprepare(trng->clk);
 	return ret;
 }