vvfat: need to use first_sectors_number to distinguish fdd/hdd This is consistent with what "real" floppies have, so file(1) now actually recognizes the VVFAT image as a 1.44 MB floppy. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>