ARM: dts: am33xx-l4: change #pinctrl-cells from 1 to 2

Increase #pinctrl-cells to 2 so that mux and conf be kept separate. This
requires the AM33XX_PADCONF macro in omap.h to also be modified to keep pin
conf and pin mux values separate.

Signed-off-by: Drew Fustini <drew@beagleboard.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Haojian Zhuang <haojian.zhuang@linaro.org>
Link: https://lore.kernel.org/r/20200701013320.130441-3-drew@beagleboard.org


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>