hwmon: (dell-smm) Simplify ioctl handler

The second switch-case has no real purpose:

- for I8K_BIOS_VERSION, val does not represent a return value,
  making the check for error values unnecessary.
- for I8K_MACHINE_ID, val remains zero, so the error check is
  unnecessary too.

Remove the switch-case and move the calls to copy_to_user()
into the first switch-case for I8K_BIOS_VERSION/_MACHINE_ID.
Omit buff[] since data->bios_machineid already contains the string
with the necessary zero padding through devm_kzalloc().

Tested on a Dell Inspiron 3505.
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Reviewed-by: Pali Rohár <pali@kernel.org>
Link: https://lore.kernel.org/r/20211211155422.16830-2-W_Armin@gmx.deSigned-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/dell-smm-hwmon.c

@@ -454,7 +454,6 @@ i8k_ioctl_unlocked(struct file *fp, struct dell_smm_data *data, unsigned int cmd
 {
 	int val = 0;
 	int speed, err;
-	unsigned char buff[16];
 	int __user *argp = (int __user *)arg;
 
 	if (!argp)
@@ -468,15 +467,19 @@ i8k_ioctl_unlocked(struct file *fp, struct dell_smm_data *data, unsigned int cmd
 
 		val = (data->bios_version[0] << 16) |
 				(data->bios_version[1] << 8) | data->bios_version[2];
-		break;
 
+		if (copy_to_user(argp, &val, sizeof(val)))
+			return -EFAULT;
+
+		return 0;
 	case I8K_MACHINE_ID:
 		if (restricted && !capable(CAP_SYS_ADMIN))
 			return -EPERM;
 
-		strscpy_pad(buff, data->bios_machineid, sizeof(buff));
-		break;
+		if (copy_to_user(argp, data->bios_machineid, sizeof(data->bios_machineid)))
+			return -EFAULT;
 
+		return 0;
 	case I8K_FN_STATUS:
 		val = i8k_get_fn_status();
 		break;
@@ -527,23 +530,8 @@ i8k_ioctl_unlocked(struct file *fp, struct dell_smm_data *data, unsigned int cmd
 	if (val < 0)
 		return val;
 
-	switch (cmd) {
-	case I8K_BIOS_VERSION:
-		if (copy_to_user(argp, &val, 4))
-			return -EFAULT;
-
-		break;
-	case I8K_MACHINE_ID:
-		if (copy_to_user(argp, buff, 16))
-			return -EFAULT;
-
-		break;
-	default:
-		if (copy_to_user(argp, &val, sizeof(int)))
-			return -EFAULT;
-
-		break;
-	}
+	if (copy_to_user(argp, &val, sizeof(int)))
+		return -EFAULT;
 
 	return 0;
 }