Revert "ARM64: toHalf() intrinsic for ARMv8"

This reverts commit 2cc0c0f4b6a76dfb1ad205cfd79efe7efe2904d6.

Reason for revert: Broke some builds. To be investigated.

Bug: 143205070
Change-Id: Ib36e149cc5ed7f53c932c0b611b43c28d19f22dc
11 files changed