rework the rotate-by-1 instructions to be defined like the

shift-by-1 instructions, where the asmstring doesn't contain
the implicit 1.  It turns out that a bunch of these rotate
instructions were completely broken because they used 1 
instead of $1.

This fixes assembly mismatches on "rclb	$1, %bl" and friends,
where we used to generate the 3 byte form, we now generate the
proper 2-byte form.

llvm-svn: 118355