ia32: Correct and clean up ia32_turn_back_dest_am().
ia32: Correct and clean up ia32_turn_back_dest_am().

There are no tests for this, so nobody noticed that the result is broken.

jonashaag/libfirm,jonashaag/libfirm,MatzeB/libfirm,MatzeB/libfirm,libfirm/libfirm,killbug2004/libfirm,8l/libfirm,jonashaag/libfirm,davidgiven/libfirm,8l/libfirm,davidgiven/libfirm,killbug2004/libfirm,libfirm/libfirm,davidgiven/libfirm,8l/libfirm,MatzeB/libfirm,MatzeB/libfirm,libfirm/libfirm,davidgiven/libfirm,jonashaag/libfirm,jonashaag/libfirm,jonashaag/libfirm,jonashaag/libfirm,killbug2004/libfirm,killbug2004/libfirm,davidgiven/libfirm,killbug2004/libfirm,8l/libfirm,MatzeB/libfirm,8l/libfirm,killbug2004/libfirm,libfirm/libfirm,8l/libfirm,davidgiven/libfirm,killbug2004/libfirm,davidgiven/libfirm,libfirm/libfirm,8l/libfirm,MatzeB/libfirm,MatzeB/libfirm