qemu.tests: Add a test case for timerdevice with boot testing

Signed-off-by: Qingtang Zhou <qzhou@redhat.com>
shared.cfg: Add timerdevice config in guest-os files

Signed-off-by: Qingtang Zhou <qzhou@redhat.com>
qemu.tests: Add test for booting with pit clock source

Signed-off-by: Qingtang Zhou <qzhou@redhat.com>
qemu.tests: Add test for timerdevice with reboot testing

Signed-off-by: Qingtang Zhou <qzhou@redhat.com>
qemu.tests: Add test for timerdevice with load on host

Signed-off-by: Qingtang Zhou <qzhou@redhat.com>