pinctrl: single: fix pinctrl_spec.args_count bounds check

The property #pinctrl-cells can either be 1 or 2:

- if #pinctrl-cells = <1>, then pinctrl_spec.args_count = 2
- if #pinctrl-cells = <2>, then pinctrl_spec.args_count = 3

All other values of pinctrl_spec.args_count are incorrect.  This fix
checks the upper bound instead of just the lower bound.

Fixes: a1339541 ("pinctrl: single: parse #pinctrl-cells = 2")
Reported-by: Trent Piepho <tpiepho@gmail.com>
Signed-off-by: Drew Fustini <drew@beagleboard.org>
Acked-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/linux-omap/3139716.CMS8C0sQ7x@zen.local/
Link: https://lore.kernel.org/r/20200930174839.1308344-1-drew@beagleboard.org


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