Revert "Disable thinlto in libbinder for riscv64 targets"

This reverts commit 383b8a54.

Reason for revert:  Not needed as emultated tls is now globally disabled https://android-review.git.corp.google.com/c/platform/build/soong/+/2431153

Change-Id: I9423d7783bfccc49876f2137c1c2fb705c165be2