disasm: Fix disassembling of evex prefix
As been pointed by @hpa evex is pretty fine in ia-32.
Quoting Peter
| This is wrong, though; EVEX is permitted in 32-bit mode just as VEX is.
| The key thing is that bits [7:5] have to be 1 in 32-bit mode. It is
| unclear what happens if these bits are 110 as that depends on if it is
| decoded using the modr/m decoder or not. For VEX prefixes we accept
| them as VEX in that case, which may not match the CPU.
This is a fix for commit
db6ecf9b76a2
Reported-by: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>