x86: tangier: pinmux: Move error message to the caller

Move error message to the caller of mrfld_pinconfig*() in order
to unify them in the future.

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>