pinctrl: mediatek: fix mode encoding

Pin modes are encoded in the SoC data structure. Use that value to set
IES SMT.

Cc: Fabien Parent <fparent@baylibre.com>
Cc: Sean Wang <sean.wang@kernel.org>
Cc: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Cc: linux-mediatek@lists.infradead.org
Fixes: 696beef7

 ("pinctrl: mediatek: move bit assignment")
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Matthias Brugger <mbrugger@suse.com>
Link: https://lore.kernel.org/r/20210608150656.29007-1-matthias.bgg@kernel.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>