kernel tools: use 4K sector size for DTB FAT image

Update build-dtb-image.sh to format the DTB FAT image with a 4096-byte logical sector size by passing `-S 4096` to mkfs.vfat.

This aligns the dtb.bin filesystem layout with 4K sector expectations on target boot flows while keeping the overall image size and DTB payload unchanged.

Signed-off-by: Bjordis Collaku <[email protected]>

Author: bjordiscollaku

kernel/scripts/build-dtb-image.sh

@@ -227,9 +227,9 @@ echo "[INFO] Using loop device: $LOOP_DEV"
 # Create a temporary mount directory for this run
 MNT_DIR="$(mktemp -d -t dtb-mnt-XXXXXX)"
 
-# Format the loop device with FAT
-echo "[INFO] Formatting $LOOP_DEV as FAT..."
-mkfs.vfat "$LOOP_DEV" >/dev/null
+# Format the loop device with FAT (4 KiB logical sector size)
+echo "[INFO] Formatting $LOOP_DEV as FAT with 4 KiB sector size..."
+mkfs.vfat -S 4096 "$LOOP_DEV" >/dev/null
 
 # Mount the loop device
 echo "[INFO] Mounting $LOOP_DEV at $MNT_DIR..."