Documentation: intel_pstate: Fix description of asymmetric packing with SMT

one core, ``intel_pstate`` assigns performance-based priorities to CPUs.  Namely,

the priority of a given CPU reflects its highest HWP performance level which

causes the CPU scheduler to generally prefer more performant CPUs, so the less

performant CPUs are used when the other ones are fully loaded.  However, SMT

siblings (that is, logical CPUs sharing one physical core) are treated in a

special way such that if one of them is in use, the effective priority of the

other ones is lowered below the priorities of the CPUs located in the other

physical cores.

performant CPUs are used when the other ones are fully loaded.  SMT siblings

(that is, logical CPUs sharing one physical core) are given the same priority.

The scheduler can pull tasks from lower-priority cores and place them on any

sibling.  Since the scheduler spreads tasks among physical cores, tasks will be

placed on the SMT siblings of physical cores only after all physical cores are

busy.

This approach maximizes performance in the majority of cases, but unfortunately

it also leads to excessive energy usage in some important scenarios, like video