x86: tangier: pinmux: Move is_protected assignment closer to its user

Move is_protected assignment closer to its user.
This increases readability and makes maintenance easier.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>