[ARM] Fix instruction selection for ARMISD::CMOV with f16 type

Summary:
In the cases where the CMOV (f16) SDNode is used with condition codes
LT, LE, VC or NE, it is successfully selected into a VSEL instruction.

In the remaining cases, however, instruction selection fails since VSEL
does not support other condition codes.

This patch handles such cases by using the single-precision version of
the VMOV instruction.

Reviewers: ostannard, dmgreen

Reviewed By: dmgreen

Subscribers: kristof.beyls, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70667