gpio: dwapb: add gpio-signaled acpi event support

This patch adds gpio-signaled acpi event support. It is used for
power button on hisilicon D02 board, an arm64 platform.

The corresponding DSDT file is defined as follows:
Device(GPI0) {
	Name(_HID, "HISI0181")
	Name(_ADR, 0)
	Name(_UID, 0)

	Name (_CRS, ResourceTemplate ()  {
		Memory32Fixed (ReadWrite, 0x802e0000, 0x10000)
		Interrupt (ResourceConsumer, Level, ActiveHigh,
		Exclusive,,,)  {344}
	})

	Device(PRTa) {
		Name (_DSD, Package () {
		Package () {
			Package () {"reg",0},
			Package () {"snps,nr-gpios",32},
		}
		})
	}

	Name (_AEI, ResourceTemplate () {
		GpioInt(Edge, ActiveLow, ExclusiveAndWake,
		PullUp, , " \\_SB.GPI0") {8}
	})

	Method (_E08, 0x0, NotSerialized) {
		Notify (\_SB.PWRB, 0x80)
	}
}

Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Jiang Qiu <qiujiang@huawei.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>