[PowerPC] Don't convert Loop to CTR Loop for fp128 BinaryOperator

Summary:
For PPC BinaryOperator of fp128 will become libcall, we shouldn't
convert loop to CTR loop if the loop contain libCall.

But currently, in the PPCTTIImpl::mightUseCTR() function, we only deal
with BinaryOperator for ppc_fp128, don't deal with the fp128.

Reviewed By: shchenz

Differential Revision: https://reviews.llvm.org/D81353