tests: watchdog: Interrupt reset mode modifications

In order for interrupt reset mode to work (reset the processor
after and interrupt) the interrupt does not has to be cleared,
and the qmsi hal layer clears the interrupt after the callback
has been invoked, the callback does not return and the processor
should reset.

Jira: ZEP-1566

Change-Id: Ic951a0f15fe95fb0ef5d752b831c62e6fa3ceea0
Signed-off-by: Sergio Rodriguez <sergio.sf.rodriguez@intel.com>