x86-64: LAR and LSL don't need REX.W

x86-64: LAR and LSL don't need REX.W

Just like we suppress emitting REX.W for e.g. MOV from/to segment
register, there's also no need for it for LAR and LSL - these can only
ever return 32-bit values and hence always zero-extend their results
anyway.

While there also drop the redundant Word from the first operand of
the second template each - this is already implied by Reg16.