i386: Do not sanitize upper part of V2HFmode and V4HFmode reg with -fno-trapping-math [PR110832]

Also add ix86_partial_vec_fp_math to to condition of V2HF/V4HF named
patterns in order to avoid generation of partial vector V8HFmode
trapping instructions.

gcc/ChangeLog:

	PR target/110832
	* config/i386/mmx.md: (movq_<mode>_to_sse): Also do not
	sanitize upper part of V4HFmode register with
	-fno-trapping-math.
	(<insn>v4hf3): Enable for ix86_partial_vec_fp_math.
	(<divv4hf3): Ditto.
	(<insn>v2hf3): Ditto.
	(divv2hf3): Ditto.
	(movd_v2hf_to_sse): Do not sanitize upper part of V2HFmode
	register with -fno-trapping-math.