Add arm64 HW instructions FMADDD, FMADDS, FMSUBD, FMSUBS, FNMADDD, FNMADDS,
FNMSUBD, FNMSUBS, VFMLA, VFMLS, VMOV (element) for math optimization.

Add check on register element index and test cases.

Change-Id: Ice07c50b1a02d488ad2cde2a4e8aea93f3e3afff
Reviewed-on: https://go-review.googlesource.com/90876Reviewed-by: Cherry Zhang <cherryyz@google.com>