Hide TelephonyRegistryManager.

This was added for telephony mainline, and as such is not needed in
R now.

Test: basic sanity
Bug: 149850449
Merged-in: I2b47ab45839f07494dcad4f1878809a55ddd3087
Change-Id: I2b47ab45839f07494dcad4f1878809a55ddd3087
(cherry picked from commit 7411d22e)