pinctrl: actions: make s900_functions, s900_padinfo and s900_pads static

s900_functions, s900_padinfo and s900_pads are local to the source and do
not need to be in global scope, so make them static.

Cleans up sparse warnings:
drivers/pinctrl/actions/pinctrl-s900.c:1445:30: warning: symbol
's900_functions' was not declared. Should it be static?
drivers/pinctrl/actions/pinctrl-s900.c:1664:20: warning: symbol
's900_padinfo' was not declared. Should it be static?
drivers/pinctrl/actions/pinctrl-s900.c:207:31: warning: symbol
's900_pads' was not declared. Should it be static?

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>