qemu-iotests: s390x: fix test 041 and 055 There is no 'ide-cd' device defined on non-pc platform, so test_medium_not_found() test should be skipped. Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Michael Mueller <mimu@linux.vnet.ibm.com> Reviewed-by: Sascha Silbe <silbe@linux.vnet.ibm.com> Signed-off-by: Xiao Guang Chen <chenxg@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>