create_legacy_bootloader_templates.sh: include search module for grub

Need 'search' command to find the correct disk.

See CL:*706333 for the use case.

BUG=b:118591758
TEST=build_image & install, boot into legacy bootloader
     verify that 'search' command exists

Change-Id: Id895f72651da2de8a1adb2bbccaab7795e72c475
Reviewed-on: https://chromium-review.googlesource.com/1309440
Commit-Ready: Ting Shen <phoenixshen@chromium.org>
Tested-by: Ting Shen <phoenixshen@chromium.org>
Reviewed-by: Joel Kitching <kitching@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
diff --git a/build_library/create_legacy_bootloader_templates.sh b/build_library/create_legacy_bootloader_templates.sh
index c1d826e..be5aff0 100755
--- a/build_library/create_legacy_bootloader_templates.sh
+++ b/build_library/create_legacy_bootloader_templates.sh
@@ -212,7 +212,7 @@
   grub_args=(
     -p /efi/boot
     part_gpt gptpriority test fat ext2 hfs hfsplus normal boot chain
-    efi_gop configfile linux
+    efi_gop configfile linux search
   )
   sudo grub-mkimage -O x86_64-efi \
     -o "${FLAGS_to}/efi/boot/bootx64.efi" "${grub_args[@]}"