insns.dat: Restore default size of memory operands

insns.dat: Restore default size of memory operands

During conversion of size of memory operands into
explicit form the compatibility with 2.07 has been
broken (for a small set of instructions). Lets restore
it. Details below.

This is due to specifics of our "fuzzy logic" algorithm.

For example consider the user wrote an instruction like

	VCVTTPD2DQ xmm0,[eax]

the last operand is memory reference. But template contains
the following two items (written in simplified form)

	VCVTTPD2DQ xmmreg,mem128
	VCVTTPD2DQ xmmreg,mem256

So this is impossible to find out what _exactly_ user meant:
either reference to 128 bit value in memory or 256 bit.

As a solution we've been using IF_Sx modifier written in
template which allows to choose "by-default" template
and break the tie.

Reported-by: Victor van den Elzen <victor.vde@gmail.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>