pinctrl: rk805: Make structures constant

pinctrl: rk805: Make structures constant

Static structures rk805_pinctrl_desc and rk805_gpio_chip, of types
gpio_chip and pinctrl_desc respectively, are not used except to be
copied into the fields of a different variable. Hence make
rk805_pinctrl_desc and rk805_gpio_chip both constant to protect them
from unintended modification.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Link: https://lore.kernel.org/r/20190819075757.1753-1-nishkadg.linux@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>