* System Controller Registers R/W driver

System controller node represents a register region containing a set
of miscellaneous registers. The registers are not cohesive enough to
represent as any specific type of device. The typical use-case is for
some other node's driver, or platform-specific code, to acquire a
reference to the syscon node (e.g. by phandle, node path, or search
using a specific compatible value), interrogate the node (or associated
OS driver) to determine the location of the registers, and access the
registers directly.

Required properties:
- compatible: Should contain "syscon".
- reg: the register region can be accessed from syscon

Optional properties:
- reg-io-width: the size (in bytes) of the IO accesses that should be
  performed on the device.
- clocks: clock used for accessing the regmap

Examples:
gpr: iomuxc-gpr@020e0000 {
	compatible = "fsl,imx6q-iomuxc-gpr", "syscon";
	reg = <0x020e0000 0x38>;
};

hsio: hsio@5f080000 {
	compatible = "fsl,imx8qm-hsio", "syscon";
	reg = <0x0 0x5f080000 0x0 0xF0000>; /* lpcg, csr, msic, gpio */
};