Extend lshifrtsi3_1_zext to ?k alternative.

Extend lshifrtsi3_1_zext to ?k alternative.

late_combine will combine lshift + zero into *lshifrtsi3_1_zext which
cause extra mov between gpr and kmask, add ?k to the pattern.

gcc/ChangeLog:

	PR target/115610
	* config/i386/i386.md (<*insnsi3_zext): Add alternative ?k,
	enable it only for lshiftrt and under avx512bw.
	* config/i386/sse.md (*klshrsi3_1_zext): New define_insn, and
	add corresponding define_split after it.