tests: disk: disk_access: align sector and erase sizes

Ensure that `sector-size` and `erase-size` match for the test.

Signed-off-by: Jordan Yates <[email protected]>

Author: JordanYates

tests/drivers/disk/disk_access/boards/native_sim.overlay

@@ -10,6 +10,7 @@
 
 &flash0 {
 	reg = <0x00000000 DT_SIZE_K(1024)>;
+	erase-block-size = <512>;
 	partitions {
 		compatible = "fixed-partitions";
 		#address-cells = <1>;