Description of problem:
Customer can check on the Readonly option for IDE disk through virt-manager, but qemu-kvm do not support it.

Version-Release number of selected component (if applicable):
virt-manager-0.9.0-14.el6.x86_64
qemu-kvm-0.12.1.2-2.292.el6.x86_64
libvirt-0.9.10-20.el6.x86_64

# uname -a
Linux daisy.redhat.com 2.6.32-270.el6.x86_64 #1 SMP Tue May 8 21:44:43 EDT 2012 x86_64 x86_64 x86_64 GNU/Linux

How reproducible:
Always.

Steps to Reproduce:
1.Prepare one normal guest.
2.Add the second IDE disk on the guest through virt-manager.
#virsh dumpxml test
...
    </disk>
    <disk type='file' device='disk'>
      <driver name='qemu' type='raw' cache='none'/>
      <source file='/var/lib/libvirt/images/disk3.img'/>
      <target dev='hda' bus='ide'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
...

3.Check on the Readonly option for the second IDE disk and click Apply button.
4.Start the guest.
# virsh start test
error: Failed to start domain test
error: internal error process exited while connecting to monitor: char device redirected to /dev/pts/13
qemu-kvm: -device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0: Can't use a read-only drive
qemu-kvm: -device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0: Device 'ide-drive' could not be initialized


Actually results:
Above as.

Expected results:
Hide the Readonly option only for IDE disk.

Additional info:
It will cause some confusion, if the customer can check on this option ,but can not use it.