Instead of allocating timer with timer_new store it directly in the
state struct. This makes it simpler to free it together with the device.

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <fd01eb3720ec32dab06e03019f72f3e177033679.1635541329.git.balaton@eik.bme.hu>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>