Hi,
I found wrong MODE_XI used in movdi_internal that cause zmm 
Generation with "-march=skylake-avx512 -mprefer-vector-width=128" 
options set. This patch fixes the mode and register type but keep using
AVX512 instruction set.

2017-11-28  Sergey Shalnov  <Sergey.Shalnov@intel.com>
gcc/
	* config/i386/i386.md: Fix AVX512 register width
	in AVX512 instruction.