fix: frdm_rw612_rw612: fix partition size

The sketch partition size was slightly overflowing the original
"image-1" partition, causing corruption on the storage partition.

Author: pillo79

variants/frdm_rw612_rw612/frdm_rw612_rw612.overlay

@@ -10,8 +10,7 @@
 	w25q512jvfiq: w25q512jvfiq@0 {
 			partitions {
 				user_sketch: partition@323000 {
-					label = "image-1";
-					reg = <0x00323000 DT_SIZE_M(3)>;
+					reg = <0x00323000 (DT_SIZE_M(3) - 0x3000)>;
 				};
 			};
 	};