gpio: Add a driver for Sodaville GPIO controller

Sodaville has GPIO controller behind the PCI bus. To my suprissed it is
not the same as on PXA.

The interrupt & gpio chip can be referenced from the device tree like
from any other driver. Unfortunately the driver which uses the gpio
interrupt has to use irq_of_parse_and_map() instead of
platform_get_irq(). The problem is that the platform device (which is
created from the device tree) is most likely created before the
interrupt chip is registered and therefore irq_of_parse_and_map() fails.

In theory the driver works as module. In reality most of the irq
functions are not exported to modules and it is possible that _this_
module is unloaded while the provided irqs are still in use.

Signed-off-by: Hans J. Koch <hjk@linutronix.de>
[torbenh@linutronix.de: make it work after the irq namespace cleanup,
	                add some device tree entries.]
Signed-off-by: Torben Hohn <torbenh@linutronix.de>
[bigeasy@linutronix.de: convert to generic irq & gpio chip]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
[grant.likely@secretlab.ca: depend on x86 to avoid irq_domain breakage]
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

arch/x86/platform/ce4100/falconfalls.dts

@@ -208,16 +208,19 @@
 					interrupts = <14 1>;
 				};
 
-				gpio@b,1 {
+				pcigpio: gpio@b,1 {
+					#gpio-cells = <2>;
+					#interrupt-cells = <2>;
 					compatible = "pci8086,2e67.2",
 						   "pci8086,2e67",
 						   "pciclassff0000",
 						   "pciclassff00";
 
-					#gpio-cells = <2>;
 					reg = <0x15900 0x0 0x0 0x0 0x0>;
 					interrupts = <15 1>;
+					interrupt-controller;
 					gpio-controller;
+					intel,muxctl = <0>;
 				};
 
 				i2c-controller@b,2 {