pinctrl: nuvoton: wpcm450: Fix handling of inverted MFSEL bits

pinctrl: nuvoton: wpcm450: Fix handling of inverted MFSEL bits

SCS3SEL and KBCCSEL use inverted logic: Whereas in other fields 0
selects the GPIO function and 1 selects the special function, in these
two fields, 0 selects the special function and 1 selects the GPIO
function.

Adjust the code to handle this quirk.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Link: https://lore.kernel.org/r/20221105185911.1547847-3-j.neuschaefer@gmx.net
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>