[AArch64] Fix BTI instruction emission.
SCTLR_EL1.BT controls the PACI[AB]SP compatibility with PBYTE 11
This bit will be set to zero so PACI[AB]SP are equal to BTI C
Reviewers: chill, tamas.petz, pbarrio, ostannard
Reviewed By: tamas.petz, ostannard
Subscribers: kristof.beyls, hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D81746