fix bug introduced in refactoring: displacement only modam used wrong modrm byte
fix bug introduced in refactoring: displacement only modam used wrong modrm byte

[r26568]

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