Remove unnecessary visibility rules

The default visibility of the repository is set in the top-level
Android.bp to `:__subpackages__`, which makes everything internal
visibility to SdkExtensions by default.

Keep only the visibility rules that expand outside the module.

Test: m nothing
Change-Id: Ib3a7b2c696ddf915f1a88071ada9463713ce1c2b
2 files changed