USB: chipidea: add imx usbmisc support

i.MX usb controllers share non-core registers, which may include
SoC specific controls. We turn it into a usbmisc device and usbmisc
driver set operations needed by ci13xxx_imx driver.

For example, Sabrelite board has bad over-current design, we can
usbmisc to disable over-current detection.

Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Richard Zhao <richard.zhao@freescale.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/Documentation/devicetree/bindings/usb/usbmisc-imx.txt b/Documentation/devicetree/bindings/usb/usbmisc-imx.txt
new file mode 100644
index 0000000..97ce94e
--- /dev/null
+++ b/Documentation/devicetree/bindings/usb/usbmisc-imx.txt
@@ -0,0 +1,14 @@
+* Freescale i.MX non-core registers
+
+Required properties:
+- #index-cells: Cells used to descibe usb controller index. Should be <1>
+- compatible: Should be one of below:
+	"fsl,imx6q-usbmisc" for imx6q
+- reg: Should contain registers location and length
+
+Examples:
+usbmisc@02184800 {
+	#index-cells = <1>;
+	compatible = "fsl,imx6q-usbmisc";
+	reg = <0x02184800 0x200>;
+};