pinctrl: rockchip: only map bank0-pull-region when pmu regmap missing

When the pmu registers are supplied through a syscon regmap we do not need
to map the registers ourself.

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>