oeqa qemurunner.py: add timeout to QMP calls

oeqa qemurunner.py: add timeout to QMP calls

When a qemu machine hangs, the QMP calls can hang for ever
too, and when this happens any failing test commands from ssh
runner may be followed by dump_monitor() calls which
then also hang. Hangs followed by hangs.

Use runqemutime at setup and run_monitor() specific timeout
for later calls.

Signed-off-by: Mikko Rapeli <mikko.rapeli@linaro.org>
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>