dt-bindings: fpga: fix freeze controller compatible in region doc

Documentation/devicetree/bindings/fpga/fpga-region.txt has an error
regarding the freeze controller bridge, secifically:

 compatible = "altr,freeze-bridge";

The compatibility string should be "altr,freeze-bridge-controller"
as set forth in altera-freeze-bridge.txt.
Signed-off-by: Alan Tull <atull@kernel.org>
Reported-by: Dalon Westergreen <dalon.westergreen@intel.com>
Acked-by: Moritz Fischer <mdf@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/fpga/fpga-region.txt

@@ -415,7 +415,7 @@ DT Overlay contains:
 			firmware-name = "base.rbf";
 
 			fpga-bridge@4400 {
-				compatible = "altr,freeze-bridge";
+				compatible = "altr,freeze-bridge-controller";
 				reg = <0x4400 0x10>;
 
 				fpga_region1: fpga-region1 {
@@ -427,7 +427,7 @@ DT Overlay contains:
 			};
 
 			fpga-bridge@4420 {
-				compatible = "altr,freeze-bridge";
+				compatible = "altr,freeze-bridge-controller";
 				reg = <0x4420 0x10>;
 
 				fpga_region2: fpga-region2 {