cpcap-core: Register the driver early in the boot process.

This might make the following block in arch/arm/boot/dts/omap3-mapphone.dtsi obsolete:
```
	regulators {
		compatible = "simple-bus";

		vmmc: fixedregulator@0 {
			compatible = "regulator-fixed";
			regulator-name = "vmmc";
			regulator-min-microvolt = <3300000>;
			regulator-max-microvolt = <3300000>;
		};
	};
```
-> has to be tested!