schemas: Make <type/> for capscsi type optional
schemas: Make <type/> for capscsi type optional

The <type/> element for <capability type='scsi'> part of nodedev
XML is optional (see udevProcessSCSIDevice()) and as such might
not be formatted into nodedev XML (see
virNodeDeviceCapSCSIDefFormat()). Reflect this in our RNG.

Signed-off-by: Michal Privoznik <83d82aaba2eed257f4814b0c239c260c4caaadf0@redhat.com>
Reviewed-by: Ján Tomko <4cab11cfb98d3c937327354a78eb07dbb6ee2bc6@redhat.com>

crobinso/libvirt,jfehlig/libvirt,jfehlig/libvirt,nertpinx/libvirt,olafhering/libvirt,nertpinx/libvirt,libvirt/libvirt,zippy2/libvirt,zippy2/libvirt,crobinso/libvirt,libvirt/libvirt,olafhering/libvirt,nertpinx/libvirt,jfehlig/libvirt,nertpinx/libvirt,zippy2/libvirt,crobinso/libvirt,olafhering/libvirt,libvirt/libvirt,libvirt/libvirt,crobinso/libvirt,jfehlig/libvirt,nertpinx/libvirt,olafhering/libvirt,zippy2/libvirt