pinctrl: add new pinconf attrs "output-high" and "output-low"

pinctrl: add new pinconf attrs "output-high" and "output-low"

PD#162858: pinctrl: add new pinconf attrs "output-high" and "output-low"

we can refer the following example to use:
mux {
	groups = "GPIOC_0", "GPIOC_1", "GPIOC_2",
		"GPIOC_3", "GPIOC_4", "GPIOC_5";
	function = "gpio_periphs";

	output-high; // or output-low
}
output-high: GPIO_EN_N[pin]=<0> and GPIO_O[pin]=<1>
output-low : GPIO_EN_N[pin]=<0> and GPIO_O[pin]=<0>

Change-Id: I3f8ec1bd1eff7c7d6e7416b608e4c5d6c7b15955
Signed-off-by: Xingyu Chen <xingyu.chen@amlogic.com>