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.de


Signed-off-by: Guenter Roeck <linux@roeck-us.net>