boards: nucleo_wb55cg: Set partition for swap f/w update method

Flash partition was defining a scratch area which was implying the use
of mcuboot BOOT_SWAP_USING_SCRATCH f/w update method.
By removing this partition, mcuboot will automatically use
BOOT_PREFER_SWAP_MOVE method which should be prefered as it levels
flash wear. Incidentally increase slot1 by one sector (as this is
preferred for the swap method).

Signed-off-by: Erwan Gouriou <erwan.gouriou@st.com>
diff --git a/boards/st/nucleo_wba55cg/nucleo_wba55cg.dts b/boards/st/nucleo_wba55cg/nucleo_wba55cg.dts
index f3ba9c4..c35ce85 100644
--- a/boards/st/nucleo_wba55cg/nucleo_wba55cg.dts
+++ b/boards/st/nucleo_wba55cg/nucleo_wba55cg.dts
@@ -173,19 +173,15 @@
 		};
 		slot0_partition: partition@10000 {
 			label = "image-0";
-			reg = <0x00010000 DT_SIZE_K(448)>;
+			reg = <0x00010000 DT_SIZE_K(456)>;
 		};
-		slot1_partition: partition@80000 {
+		slot1_partition: partition@82000 {
 			label = "image-1";
-			reg = <0x00080000 DT_SIZE_K(448)>;
+			reg = <0x00082000 DT_SIZE_K(448)>;
 		};
-		scratch_partition: partition@f0000 {
-			label = "image-scratch";
-			reg = <0x000f0000 DT_SIZE_K(16)>;
-		};
-		storage_partition: partition@f4000 {
+		storage_partition: partition@f2000 {
 			label = "storage";
-			reg = <0x000f4000 DT_SIZE_K(48)>;
+			reg = <0x000f2000 DT_SIZE_K(56)>;
 		};
 	};
 };