sse.md (VI48_AVX512F): New.

sse.md (VI48_AVX512F): New.

        * config/i386/sse.md (VI48_AVX512F): New.
        (VI48_AVX2): Changed to ...
        (VI48_AVX2_48_AVX512F): This.
        (avx2_ashrv<mode>): Changed to ...
        (<avx2_avx512f>_ashrv<mode>): This.
        (avx2_<shift_insn>v<mode>): Changed to ...
        (<avx2_avx512f>_<shift_insn>v<mode>): This.

Co-Authored-By: Andrey Turetskiy <andrey.turetskiy@intel.com>
Co-Authored-By: Anna Tikhonova <anna.tikhonova@intel.com>
Co-Authored-By: Ilya Tocar <ilya.tocar@intel.com>
Co-Authored-By: Ilya Verbin <ilya.verbin@intel.com>
Co-Authored-By: Kirill Yukhin <kirill.yukhin@intel.com>
Co-Authored-By: Maxim Kuznetsov <maxim.kuznetsov@intel.com>
Co-Authored-By: Michael Zolotukhin <michael.v.zolotukhin@intel.com>
Co-Authored-By: Sergey Lega <sergey.s.lega@intel.com>
From-SVN: r203435