Clock bindings for ST-Ericsson U300 System Controller Clocks

Bindings for the gated system controller clocks:

Required properties:
- compatible: must be "stericsson,u300-syscon-clk"
- #clock-cells: must be <0>
- clock-type: specifies the type of clock:
  0 = slow clock
  1 = fast clock
  2 = rest/remaining clock
- clock-id: specifies the clock in the type range

Optional properties:
- clocks: parent clock(s)

The available clocks per type are as follows:

Type:  ID:   Clock:
-------------------
0      0     Slow peripheral bridge clock
0      1     UART0 clock
0      4     GPIO clock
0      6     RTC clock
0      7     Application timer clock
0      8     Access timer clock

1      0     Fast peripheral bridge clock
1      1     I2C bus 0 clock
1      2     I2C bus 1 clock
1      5     MMC interface peripheral (silicon) clock
1      6     SPI clock

2      3     CPU clock
2      4     DMA controller clock
2      5     External Memory Interface (EMIF) clock
2      6     NAND flask interface clock
2      8     XGAM graphics engine clock
2      9     Shared External Memory Interface (SEMI) clock
2      10    AHB Subsystem Bridge clock
2      12    Interrupt controller clock

Example:

gpio_clk: gpio_clk@13M {
	#clock-cells = <0>;
	compatible = "stericsson,u300-syscon-clk";
	clock-type = <0>; /* Slow */
	clock-id = <4>;
	clocks = <&slow_clk>;
};

gpio: gpio@c0016000 {
	compatible = "stericsson,gpio-coh901";
	(...)
	clocks = <&gpio_clk>;
};