boards: nxp: frdm_mcxn236: Fix unit and first address mismatch

This fixes the following warning:

> unit address and first address in 'reg' (0x88000) don't match for
> <snip>/flash-controller@43000/flash@0/partitions/partition@80000

Signed-off-by: Reto Schneider <[email protected]>

Author: rettichschnidi

boards/nxp/frdm_mcxn236/frdm_mcxn236.dtsi

@@ -107,7 +107,7 @@
 			label = "image-0";
 			reg = <0x00010000 DT_SIZE_K(480)>;
 		};
-		slot1_partition: partition@80000 {
+		slot1_partition: partition@88000 {
 			label = "image-1";
 			reg = <0x0088000 DT_SIZE_K(472)>;
 		};