objdump, amd64: "d5 ..." can be disassembled as seto incorrectly sometimes

[Alexey Dobriyan]

Steps to reproduce:

        $ echo -e 'f:.byte 0xd5,0x90,0x90,0x90,0x90,0x90,0x90,0x90,0x90' |\
        gcc -xassembler -c -o 1.o -

        $ objdump -dr 1.o
        0000000000000000 <f>:
           0:   d5 90 90 90 90 90 90    seto   BYTE PTR [r16-0x6f6f6f70]
           7:   90
           8:   90                      nop


"d5" was aad instruction on i386 which is unsupported on amd64,
it should decode as #UD.

seto is very incorrent: seto starts with "0f 90", not d5.