[nrf fromtree] dts: nordic: nrf54h20_enga: Add erase-block-size to mram1x

The MRAM has no concept of erase blocks or pages, so this is treated as
driver configuration.

Signed-off-by: Grzegorz Swiderski <[email protected]>
(cherry picked from commit beab89d)

Author: 57300

dts/common/nordic/nrf54h20_enga.dtsi

@@ -96,6 +96,7 @@
 		mram1x: mram@e000000 {
 			compatible = "nordic,mram";
 			reg = <0xe000000 DT_SIZE_K(2048)>;
+			erase-block-size = <4096>;
 			write-block-size = <16>;
 		};