pinctrl: rockchip: do not require 2nd register area

Deprecate secondary register area for rk3188 pulls. Instead use big enough
initial mapping of grf registers to catch all.

The now deprecated register is still supported though.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Max Schwarz <max.schwarz@online.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>