tests: fix tracing.osawareness.openocd for SMP platforms

The tracing.osawareness.openocd doesn't support executing
on multicore Zephyr. However we disable multiple CPUs
usage in two different ways for this test:
 - by setting CONFIG_MP_NUM_CPUS to 1
 - by setting CONFIG_SMP to n

It's not correct for all SMP platforms to disable SMP. As
it is also excessive (we can guarantee the execution on
single core by setting CONFIG_MP_NUM_CPUS=1) let's drop
SMP disabling.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Evgeniy Paltsev <PaltsevEvgeniy@gmail.com>