x86: fix {,V}MOV{L,H}PD disassembly

x86: fix {,V}MOV{L,H}PD disassembly

Neither the legacy nor the VEX-encoded forms are permitted with register
operands, just like is already the case for their store forms as well as
{,V}MOV{L,H}PS.

At the same time, besides folding respective vex_len_table[] entries,
adjust adjacent related legacy mod_table[] entries:
- when the prefix was already decoded, PREFIX_OPCODE is pointless,
- limit the amount of string literals by using X consistently on all
  {,V}MOV{L,H}P{S,D} forms.