[AArch64] Properly validate the reciprocal estimation.

Add check for legal data types when expanding into a Newton series.

Differential Revision: https://reviews.llvm.org/D22267

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@276041 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed