XorShift128:  Add some protection to handle the case where this logic could be called from the interrupt level.

sched/sched_cpuload_oneshot:  Use the oneshot timer with optional entropy to measuer cPU load if so configured.

Add missing eth support in stm32butterfly2/nshnet config

Fix compilation warnings for stm32 eth with certain configs

Fix wrong config for stm32butterfly2/nshusbhost

add stm32butterfly2 development board

Change stm32 adc dma callback to send channel number instead of index

Revert "sam_tc_clockselect() reworked to calculate frequency error using smallest possible divisor minimizing the frequency error rather than largest possible divisor which maximized the error."

This reverts commit 5d5851a5.