pinctrl: single: parse #pinctrl-cells = 2

pinctrl: single: parse #pinctrl-cells = 2

If "pinctrl-single,pins" has 3 arguments (offset, conf, mux), then
pcs_parse_one_pinctrl_entry() does an OR operation on conf and mux to
get the value to store in the register.

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/20200701013320.130441-2-drew@beagleboard.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>