p4wq: add support for per-CPU, per-queue and delayed threads

Currently P4WQ supports queues with sets of user-provided
worked threads of arbitrary numbers. These threads are started
immediately upon initialisation.

This patch adds support for 3 more thread implementation options:

1. queue per thread. It adds a K_P4WQ_ARRAY_DEFINE() macro which
   initialises an array of queues and threads of the same number.
   These threads are then uniquely assigned to respective queues.
2. delayed start. With this option threads aren't started
   immediately upon queue initialisation. Instead a new function
   k_p4wq_enable_static_thread() has to be called to enable those
   threads individually.
3. queue per CPU. With this option the user can assign CPU masks
   to threads when calling k_p4wq_enable_static_thread().
   Otherwise the cpu_mask parameter to that function is ignored.
   Currently enabling this option implies option 2 above. Also so
   far to enable queues per CPU the user has to use
   K_P4WQ_ARRAY_DEFINE(), which means this option also implies 1
   above, but both these restrictions can be relaxed in the
   future if required.

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
2 files changed