update t440p script

coreboot-t440p/steps/combine_bios.sh

@@ -0,0 +1,27 @@
+#!/bin/sh
+# Step: Combine BIOS chip images into a single ROM
+
+step_combine_bios() {
+  section "Combine BIOS Images"
+
+  cd "$WORK_DIR" || return 1
+
+  info "Combining 8MB (bottom) + 4MB (top) into a single 12MB ROM..."
+  run_cmd "cat 8mb_backup1.bin 4mb_backup1.bin > t440p-original.rom" || return 1
+
+  _size=$(wc -c < t440p-original.rom)
+  info "Combined ROM size: $_size bytes"
+
+  if [ "$_size" -eq "$SIZE_12MB" ]; then
+    success "ROM size correct (12MB)."
+  else
+    warn "ROM size is not 12MB ($_size bytes). This may indicate an issue."
+    if ! prompt_yes_no "Continue anyway?"; then
+      return 1
+    fi
+  fi
+
+  success "Original BIOS saved: $WORK_DIR/t440p-original.rom"
+  echo ""
+  warn "Keep this file safe! You will need it if you ever want to revert."
+}