I found slew of some pins can not be set in MCF54418. For example, the DSPI0_PCS2 and DSPI0_PCS3 are not available in any SRCR(Slew Rate Control Register). In SRCR_DSPI0, DSPI0_PCS0 and DSPI0_PCS1 are available, but not DSPI0_PCS2 and DSPI0_PCS3. In SRCR_IRQ0, IRQ1,4,6,7 are available, but not IRQ2,3. The default rise/falling time is 200ns, that is too slow. How can I set the slew of these pins?