By importing `_time` in `freertos_sleep()`, the host time module was
imported as `time` again as well, breaking all later code using e.g.
`time.ticks_ms()`.
Fix this by using `time` in `sys_kernel.freertos_sleep()` as well.
By importing `_time` in `freertos_sleep()`, the host time module was
imported as `time` again as well, breaking all later code using e.g.
`time.ticks_ms()`.
Fix this by using `time` in `sys_kernel.freertos_sleep()` as well.
