Add binder32bit to vndk_prebuilt module

For a vndk_prebuilt module that was built with 32 bit binder, add
"binder32bit: true" to its Android.bp module.
This will add .binder32 suffix to the name.

Bug: 74362637
Bug: 80450527
Test: m -j vndk_snapshot_package
Change-Id: I81049adbf5e67fe5e63d5ea3a8b027aaf6eb355b