freertos spinlock/portmux: Reduce spinlocking overhead

freertos spinlock/portmux: Reduce spinlocking overhead

Ref TW7117

Microbenchmarks in unit tests:

(All numbers in cycles per benchmarked operation):

Release mode
No lock contention lock/unlock -       301 -> 167 (-45%)
Recursive no contention lock/unlock -  289 -> 148 (-49%)
Lock contention two CPUs (lock/unlock) 699 -> 400 (-43%)

Debug mode
No lock contention lock/unlock -       355 -> 203 (-43%)
Recursive no contention lock/unlock -  345 -> 188 (-46%)
Lock contention two CPUs (lock/unlock) 761 -> 483 (-36%)