dt: bindings: add MARVELL's sd8xxx wireless device

Add device tree binding documentation for MARVELL's sd8xxx
(sd8897 and sd8997) wlan chip.
Signed-off-by: Xinming Hu <huxm@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

Documentation/devicetree/bindings/net/wireless/marvell-sd8xxx.txt

+Marvell 8897/8997 (sd8897/sd8997) SDIO devices
+------
+
+This node provides properties for controlling the marvell sdio wireless device.
+The node is expected to be specified as a child node to the SDIO controller that
+connects the device to the system.
+
+Required properties:
+
+  - compatible : should be one of the following:
+	* "marvell,sd8897"
+	* "marvell,sd8997"
+
+Optional properties:
+
+  - marvell,caldata* : A series of properties with marvell,caldata prefix,
+		      represent calibration data downloaded to the device during
+		      initialization. This is an array of unsigned 8-bit values.
+		      the properties should follow below property name and
+		      corresponding array length:
+	"marvell,caldata-txpwrlimit-2g" (length = 566).
+	"marvell,caldata-txpwrlimit-5g-sub0" (length = 502).
+	"marvell,caldata-txpwrlimit-5g-sub1" (length = 688).
+	"marvell,caldata-txpwrlimit-5g-sub2" (length = 750).
+	"marvell,caldata-txpwrlimit-5g-sub3" (length = 502).
+  - marvell,wakeup-pin : a wakeup pin number of wifi chip which will be configured
+		      to firmware. Firmware will wakeup the host using this pin
+		      during suspend/resume.
+  - interrupt-parent: phandle of the parent interrupt controller
+  - interrupts : interrupt pin number to the cpu. driver will request an irq based on
+		 this interrupt number. during system suspend, the irq will be enabled
+		 so that the wifi chip can wakeup host platform under certain condition.
+		 during system resume, the irq will be disabled to make sure
+		 unnecessary interrupt is not received.
+
+Example:
+
+Tx power limit calibration data is configured in below example.
+The calibration data is an array of unsigned values, the length
+can vary between hw versions.
+IRQ pin 38 is used as system wakeup source interrupt. wakeup pin 3 is configured
+so that firmware can wakeup host using this device side pin.
+
+&mmc3 {
+	status = "okay";
+	vmmc-supply = <&wlan_en_reg>;
+	bus-width = <4>;
+	cap-power-off-card;
+	keep-power-in-suspend;
+
+	#address-cells = <1>;
+	#size-cells = <0>;
+	mwifiex: wifi@1 {
+		compatible = "marvell,sd8897";
+		reg = <1>;
+		interrupt-parent = <&pio>;
+		interrupts = <38 IRQ_TYPE_LEVEL_LOW>;
+
+		marvell,caldata_00_txpwrlimit_2g_cfg_set = /bits/ 8 <
+	0x01 0x00 0x06 0x00 0x08 0x02 0x89 0x01>;
+		marvell,wakeup-pin = <3>;
+	};
+};