mmc: sdhci-esdhc-imx: add device tree probe support

The patch adds device tree probe support for sdhci-esdhc-imx driver.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: Wolfram Sang <w.sang@pengutronix.de>
Cc: Chris Ball <cjb@laptop.org>
Cc: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Chris Ball <cjb@laptop.org>

Documentation/devicetree/bindings/mmc/fsl-imx-esdhc.txt

@@ -0,0 +1,34 @@
+* Freescale Enhanced Secure Digital Host Controller (eSDHC) for i.MX
+
+The Enhanced Secure Digital Host Controller on Freescale i.MX family
+provides an interface for MMC, SD, and SDIO types of memory cards.
+
+Required properties:
+- compatible : Should be "fsl,<chip>-esdhc"
+- reg : Should contain eSDHC registers location and length
+- interrupts : Should contain eSDHC interrupt
+
+Optional properties:
+- fsl,card-wired : Indicate the card is wired to host permanently
+- fsl,cd-internal : Indicate to use controller internal card detection
+- fsl,wp-internal : Indicate to use controller internal write protection
+- cd-gpios : Specify GPIOs for card detection
+- wp-gpios : Specify GPIOs for write protection
+
+Examples:
+
+esdhc@70004000 {
+	compatible = "fsl,imx51-esdhc";
+	reg = <0x70004000 0x4000>;
+	interrupts = <1>;
+	fsl,cd-internal;
+	fsl,wp-internal;
+};
+
+esdhc@70008000 {
+	compatible = "fsl,imx51-esdhc";
+	reg = <0x70008000 0x4000>;
+	interrupts = <2>;
+	cd-gpios = <&gpio0 6 0>; /* GPIO1_6 */
+	wp-gpios = <&gpio0 5 0>; /* GPIO1_5 */
+};