hwrng: exynos - Fix unbalanced PM runtime get/puts

Currently this driver calls pm_runtime_get_sync() rampantly
but never puts anything back. This makes it impossible for the
device to autosuspend properly; it will remain fully active
after the first use.

Fix in the obvious way.

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Kukjin Kim <kgene@kernel.org>
Cc: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Tested-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/exynos-rng.c

@@ -95,7 +95,7 @@ static int exynos_read(struct hwrng *rng, void *buf,
 	*data = exynos_rng_readl(exynos_rng, EXYNOS_PRNG_OUT1_OFFSET);
 
 	pm_runtime_mark_last_busy(exynos_rng->dev);
-	pm_runtime_autosuspend(exynos_rng->dev);
+	pm_runtime_put_sync_autosuspend(exynos_rng->dev);
 
 	return 4;
 }