ARM: dts: AM33XX: Add MMC support and documentation

Adds AM33XX MMC support for am335x-bone, am335x-evm and am335x-evmsk boards.

Also added is the DMA binding definitions based on the generic DMA request
binding.

Additional changes made to DTS:
* Interrupt, reg and compatible properties added
* ti,needs-special-hs-handling added

Signed-off-by: Matt Porter <mporter@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Joel Fernandes <joelf@ti.com>
Signed-off-by: Benoit Cousson <bcousson@baylibre.com>
diff --git a/arch/arm/boot/dts/am335x-evm.dts b/arch/arm/boot/dts/am335x-evm.dts
index e8ec875..bc4a69d 100644
--- a/arch/arm/boot/dts/am335x-evm.dts
+++ b/arch/arm/boot/dts/am335x-evm.dts
@@ -477,6 +477,8 @@
 		};
 
 		vmmc_reg: regulator@12 {
+			regulator-min-microvolt = <1800000>;
+			regulator-max-microvolt = <3300000>;
 			regulator-always-on;
 		};
 	};
@@ -517,3 +519,8 @@
 		ti,adc-channels = <4 5 6 7>;
 	};
 };
+
+&mmc1 {
+	status = "okay";
+	vmmc-supply = <&vmmc_reg>;
+};