small decode optimization

git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@11786 6c8e4198-a580-4521-a02f-c9ae86df1db9
oops, typo bug in prev commit

git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@11787 6c8e4198-a580-4521-a02f-c9ae86df1db9