[X86][MC] Intel syntax: accept implicit memory operand sizes larger than 80.

The X86AsmParser intel handling was refactored in r216481, making it
try each different memory operand size to see which one matches.
Operand sizes larger than 80 ("[xyz]mmword ptr") were forgotten, which
led to an "invalid operand" error for code such as:
  movdqa [rax], xmm0