FPGA Bridge Device Tree Binding

Optional properties:
- bridge-enable		: 0 if driver should disable bridge at startup
			  1 if driver should enable bridge at startup
			  Default is to leave bridge in current state.

Example:
	fpga_bridge3: fpga-bridge@ffc25080 {
		compatible = "altr,socfpga-fpga2sdram-bridge";
		reg = <0xffc25080 0x4>;
		bridge-enable = <0>;
	};
