Add libvendorsupport to `deps` of `generic_system_image`

libvendorsupport is an llndk library, which gets installed by the
llndk_in_system androidmk module in the kati built installed image. Add
this library explicitly to the deps of the soong built system image.

Test: Ran the filelistdiff tool
Bug: 369678122
Change-Id: I6a520ad9a934305a900a137e3e518984d6a84d8c