Revert "[ELF][PPC64] Don't perform toc-indirect to toc-relative relax... "

This reverts commit 03ffe586.

Full tile of reverted commit is:
[ELF][PPC64] Don't perform toc-indirect to toc-relative relaxation for
R_PPC64_TOC16_HA not followed by R_PPC64_TOC16_LO_DS

Breaks the multistage lld PowerPC buildbot.