x86emul: support AVX512{F,BW,_VBMI} full permute insns

x86emul: support AVX512{F,BW,_VBMI} full permute insns

Take the liberty and also correct the (public interface) name of the
AVX512_VBMI feature flag, on the assumption that no external consumer
has actually been using that flag so far. Furthermore make it have
AVX512BW instead of AVX512F as a prerequisite, for requiring full
64-bit mask registers (the upper 48 bits of which can't be accessed
other than through XSAVE/XRSTOR without AVX512BW support).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>