tests: schedule_api adapt to slow ticks

This test case is has a tolerance of 1ms, but systems with a tick slower
than 1000 ticks/sec may spil outside the 1ms tolerance.
Tolerance adapts to system's ticks/sec, e.g. QEMU targets have
100ticks/sec -> tolerance is 10ms.

Signed-off-by: Andrei Gansari <andrei.gansari@nxp.com>