boards: arduino: nicla_vision: Fix partition size.

With the current config, a debug loader overwrites the sketch.

The correct partition layout is (offset, size):
- 0x00000 - 0x40000 (256KB): Bootloader
- 0x40000 - 0xa0000 (640KB): llext loader
- 0xe0000 - 0x20000 (128KB): sketch

Signed-off-by: Ibrahim Abdalkader <[email protected]>

Author: iabdalkader

boards/arduino/nicla_vision/arduino_nicla_vision_stm32h747xx_m7.dts

@@ -150,7 +150,7 @@ zephyr_i2c: &i2c1 {
 
 		slot0_partition: partition@40000 {
 			label = "image-0";
-			reg = <0x40000 0x000c0000>;
+			reg = <0x40000 0x000a0000>;
 		};
 	};
 };