soc: silabs: siwx91x: Change memory partition

The current configuration allocate 476kB (672 − 196) to the NWP. This
configuration is only required with offloaded network stack
(CONFIG_WIFI_SILABS_SIWX91X_NET_STACK_OFFLOAD).

Since this parameter is not set by default, increase memory allocated to
Zephyr.

Signed-off-by: Jérôme Pouiller <[email protected]>

Author: jerome-pouiller

dts/arm/silabs/siwg917.dtsi

@@ -39,7 +39,7 @@
 		 * Less memory is allocated to Zephyr, more memory is allocated
 		 * to NWP, better are the WiFi and BLE performances.
 		 */
-		reg = <0x00000000 DT_SIZE_K(196)>;
+		reg = <0x00000000 DT_SIZE_K(256)>;
 	};
 
 	sram_dma1: memory-dma@24061c00 {