Mnemonic: CLEAR1 reg/mem,CL/immediate

          CLEAR1 r/m8,imm3 : 0F 1A [mod:000:r/m] imm  (6/15 clocks)
          CLEAR1 r/m16,CL  : 0F 13 [mod:000:r/m]      (5/14 clocks)
          CLEAR1 r/m16,imm4: 0F 1B [mod:000:r/m] imm  (6/15 clocks)
          CLEAR1 CY        : F8   (NEC nomenclature for Intel's CLC)
          CLEAR1 DIR       : FC   (NEC nomenclature for Intel's CLD)