vendor_kernel_boot: Update releasetools for vendor_kernel_boot

add_img_to_target_files.py will re-make image and build a new
signed vbmeta.img with new images in target-file.
We need to add vendor_kernel_boot into AVB signing list and make it
support that image.

Test: make dist -j110 and check vbmeta.img
Bug: 214409109
Signed-off-by: Lucas Wei <lucaswei@google.com>
Change-Id: Id07433f3dc33f95e2edd49de890f1e098cb9ef31
diff --git a/tools/releasetools/sign_target_files_apks.py b/tools/releasetools/sign_target_files_apks.py
index c803340..6af7486 100755
--- a/tools/releasetools/sign_target_files_apks.py
+++ b/tools/releasetools/sign_target_files_apks.py
@@ -226,6 +226,7 @@
     'pvmfw': 'avb_pvmfw_add_hash_footer_args',
     'vendor': 'avb_vendor_add_hashtree_footer_args',
     'vendor_boot': 'avb_vendor_boot_add_hash_footer_args',
+    'vendor_kernel_boot': 'avb_vendor_kernel_boot_add_hash_footer_args',
     'vendor_dlkm': "avb_vendor_dlkm_add_hashtree_footer_args",
     'vbmeta': 'avb_vbmeta_args',
     'vbmeta_system': 'avb_vbmeta_system_args',