tests: gnss: Add F9P node to build-all test

For build-time validation.

Signed-off-by: Luis Ubieda <luisf@croxel.com>

Author: ubieda

tests/drivers/build_all/gnss/app.overlay

@@ -31,6 +31,9 @@
 			gnss_m8: m8 {
 				compatible = "u-blox,m8";
 			};
+			gnss_f9p: f9p {
+				compatible = "u-blox,f9p";
+			};
 		};
 	};
 };