fastboot: support vbmeta_vendor.img

Bug: 181909612
Test: build
Change-Id: If61fff1c83513d71605c0cef2737a38f7575d69b
diff --git a/fastboot/fastboot.cpp b/fastboot/fastboot.cpp
index e5319a5..6a49fdf 100644
--- a/fastboot/fastboot.cpp
+++ b/fastboot/fastboot.cpp
@@ -166,6 +166,11 @@
                                       "vbmeta_system.sig",
                                                       "vbmeta_system",
                                                                   true,  ImageType::BootCritical },
+    { "vbmeta_vendor",
+                  "vbmeta_vendor.img",
+                                      "vbmeta_vendor.sig",
+                                                      "vbmeta_vendor",
+                                                                  true,  ImageType::BootCritical },
     { "vendor",   "vendor.img",       "vendor.sig",   "vendor",   true,  ImageType::Normal },
     { "vendor_boot",
                   "vendor_boot.img",  "vendor_boot.sig",