* Use polled waiting on platforms that support it
Due to context switching overhead waiting a very short amount of time on
a sleeping thread is often not accurate and in fact not usable for timing
critical usage i.e. in a driver. Thus we use polled waiting for ranges
in the us range on platforms that support it instead. The fallback is
the thread sleeping mechanism.
This includes:
* ARM platforms with CYCCNT register (ARMv7, ARMv8) this is
incremented at CPU clock frequency
* GD32VF103 RISC-V port with CSR_MCYCLE register this is incremented at
CPU clock frequency
* RP2040 ARMv6 port which uses the integrated timer peripheral which is
incremented with a fixed 1MHz frequency
* Use wait_us() instead of chSysPolledDelayX
...as it is powered by busy waiting now.
* Add chibios waiting methods test bench
Stefan Kerkmann
Joel Challis