dt-bindings: bus: imx-weim: document multiple address ranges per child node

Timing property for child nodes. It is mandatory, not optional.

 - fsl,weim-cs-timing:	The timing array, contains timing values for the

			child node. We can get the CS index from the child

			node's "reg" property. The number of registers depends

			on the selected chip.

			child node. We get the CS indexes from the address

			ranges in the child node's "reg" property.

			The number of registers depends on the selected chip:

			For i.MX1, i.MX21 ("fsl,imx1-weim") there are two

			registers: CSxU, CSxL.

			For i.MX25, i.MX27, i.MX31 and i.MX35 ("fsl,imx27-weim")

					0x0000c000 0x1404a38e 0x00000000>;

		};

	};

Example for an imx6q-based board, a multi-chipselect device connected to WEIM:

In this case, both chip select 0 and 1 will be configured with the same timing

array values.

	weim: weim@21b8000 {

		compatible = "fsl,imx6q-weim";

		reg = <0x021b8000 0x4000>;

		clocks = <&clks 196>;

		#address-cells = <2>;

		#size-cells = <1>;

		ranges = <0 0 0x08000000 0x02000000

			  1 0 0x0a000000 0x02000000

			  2 0 0x0c000000 0x02000000

			  3 0 0x0e000000 0x02000000>;

		fsl,weim-cs-gpr = <&gpr>;

		acme@0 {

			compatible = "acme,whatever";

			reg = <0 0 0x100>, <0 0x400000 0x800>,

				<1 0x400000 0x800>;

			fsl,weim-cs-timing = <0x024400b1 0x00001010 0x20081100

				0x00000000 0xa0000240 0x00000000>;

		};

	};