implemented few more avx-512 cvt opcodes

git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@12127 6c8e4198-a580-4521-a02f-c9ae86df1db9
Connecting USB CD-ROM without media present now supported
TODO #1: implement seek timing similar to ATA/ATAPI
TODO #2: implement asynchronus i/o in lowlevel cdrom


git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@12128 6c8e4198-a580-4521-a02f-c9ae86df1db9