memory: samsung: exynos5422-dmc: Avoid some over memory allocation

'dmc->counter' is a 'struct devfreq_event_dev **', so there is some
over memory allocation. 'counters_size' should be computed with
'sizeof(struct devfreq_event_dev *)'.

Use 'sizeof(*dmc->counter)' instead to fix it.

While at it, use devm_kcalloc() instead of devm_kzalloc()+open coded
multiplication.

Fixes: 6e7674c3 ("memory: Add DMC driver for Exynos5422")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/69d7e69346986e2fdb994d4382954c932f9f0993.1647760213.git.christophe.jaillet@wanadoo.frSigned-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

drivers/memory/samsung/exynos5422-dmc.c

@@ -1322,7 +1322,6 @@ static int exynos5_dmc_init_clks(struct exynos5_dmc *dmc)
  */
 static int exynos5_performance_counters_init(struct exynos5_dmc *dmc)
 {
-	int counters_size;
 	int ret, i;
 
 	dmc->num_counters = devfreq_event_get_edev_count(dmc->dev,
@@ -1332,8 +1331,8 @@ static int exynos5_performance_counters_init(struct exynos5_dmc *dmc)
 		return dmc->num_counters;
 	}
 
-	counters_size = sizeof(struct devfreq_event_dev) * dmc->num_counters;
-	dmc->counter = devm_kzalloc(dmc->dev, counters_size, GFP_KERNEL);
+	dmc->counter = devm_kcalloc(dmc->dev, dmc->num_counters,
+				    sizeof(*dmc->counter), GFP_KERNEL);
 	if (!dmc->counter)
 		return -ENOMEM;