[PowerPC] Enable default support of quad precision operations

Summary: Remove option guarding support of quad precision operations.

Reviewers: nemanjai, #powerpc, steven.zhang

Reviewed By: nemanjai, #powerpc, steven.zhang

Subscribers: qiucf, wuzish, nemanjai, hiraditya, kbarton, shchenz, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D83437