Mark vndkLibrariesTxt modules as device modules

vndkcorevariant.libraries.txt needs to be installed onto the device,
mark the vndkLibrariesTxt module type as a device module so that
PathForModuleInstall returns a path in the system partition.

Bug: 204136549
Test: m checkbuild
Change-Id: Ic2aadff27cee6a5e6352ceaf61b707ad3e5b531f