platform/x86: intel_pmc_ipc: Propagate error from kstrtoul()

kstrtoul() already returns negative error if the input was not valid so
return it directly.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/platform/x86/intel_pmc_ipc.c

@@ -512,8 +512,9 @@ static ssize_t intel_pmc_ipc_northpeak_store(struct device *dev,
 	int subcmd;
 	int ret;
 
-	if (kstrtoul(buf, 0, &val))
-		return -EINVAL;
+	ret = kstrtoul(buf, 0, &val);
+	if (ret)
+		return ret;
 
 	if (val)
 		subcmd = 1;