[PowerPC] remove the ctr clobbers check related to TLS access

Dynamic tls access model will be lowered to MI which clobbers CTR in
the loop in ISEL(ADDItlsgdLADDR) and post-isel CTR loop pass will revert
the loop to a normal compare + branch form.

So no need to add this clobber check in hardware loop insertion pass now.

Reviewed By: nemanjai

Differential revision: https://reviews.llvm.org/D140367