tests/queue: tests/lifo_usage: Address ADSP/coherence issues

These tests would pass pointers to data on their own stacks to other
threads, which is forbidden when CONFIG_KERNEL_COHERENCE (because
stack memory isn't cache-coherent).  Make the variables static.

Also, queue had two sleeps of 2 ticks (having been written in an era
where that meant "20-30ms"), and on a device with a 50 kHz tick rate
that's not very much time at all.  It would sometimes fail spuriously
because the spawned threads didn't consume the queue entries in time.
How about 10ms of real time instead?

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>