x86: drop dq{b,d}_mode

x86: drop dq{b,d}_mode

Their sole use is for {,V}EXTRACTPS / {,V}P{EXT,INS}RB respectively; for
consistency also limit use of dqw_mode to Jdqw. 64-bit disassembly
reflecting REX.W / VEX.W is not in line with the assembler's opcode
table having NoRex64 / VexWIG in all respective templates, i.e. assembly
input isn't being honored there either. Obviously the 0FC5 encodings of
{,V}PEXTRW then also need adjustment for consistency reasons.