qemu_x86: Use Qemu Q35 machine feature (ICH9)

Using very old machine does not make sense anymore. Switch to the new
Q35 (https://wiki.qemu.org/Features/Q35

). Among other things it allows
to test SMBus and watchdog.

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>