boards: mcxw23: Use SYSTICK as the default kernel timer

SYSTICK is used as the default kernel timer.
The FRO 1M clock source for OSTIMER is trimmed to ± 15%
accuracy over the entire voltage and temperature. The FRO 1M
is not accurate enough on the silicon.

Signed-off-by: Allen Zhang <chunfeng.zhang@nxp.com>