Pull in r263169 from upstream llvm trunk (by Tim Northover):

AArch64: only try to use scaled fcvt ops on legal vector types.

Before we ended up calling getSimpleVectorType on a <3 x float>, which
asserted.

This fixes an assertion when building the print/ghostscript9-agpl-base
port for AArch64.

PR: 213865
MFC after: 3 days