pinctrl: nomadik: hide unused functions

The nomadik pinctrl driver has two functions that are only used
for debugfs output and are otherwise unused:

drivers/pinctrl/nomadik/pinctrl-abx500.c:194:12: error: 'abx500_get_pull_updown' defined but not used
drivers/pinctrl/nomadik/pinctrl-abx500.c:471:12: error: 'abx500_get_mode' defined but not used

This makes the function definitions conditional to avoid the
harmless warnings.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>