Set FlexBus Clock Divider to correct value for 16, 8, 4 MHz

teensy3/mk20dx128.c

 #elif F_CPU == 16000000
 	// config divisors: 16 MHz core, 16 MHz bus, 16 MHz flash
   #if defined(KINETISK)
-	SIM_CLKDIV1 = SIM_CLKDIV1_OUTDIV1(0) | SIM_CLKDIV1_OUTDIV2(0) | SIM_CLKDIV1_OUTDIV4(0);
+	SIM_CLKDIV1 = SIM_CLKDIV1_OUTDIV1(0) | SIM_CLKDIV1_OUTDIV2(0) | SIM_CLKDIV1_OUTDIV3(0) | SIM_CLKDIV1_OUTDIV4(0);
   #elif defined(KINETISL)
 	SIM_CLKDIV1 = SIM_CLKDIV1_OUTDIV1(0) | SIM_CLKDIV1_OUTDIV4(0);
   #endif
 #elif F_CPU == 8000000
 	// config divisors: 8 MHz core, 8 MHz bus, 8 MHz flash
   #if defined(KINETISK)
-	SIM_CLKDIV1 = SIM_CLKDIV1_OUTDIV1(1) | SIM_CLKDIV1_OUTDIV2(1) | SIM_CLKDIV1_OUTDIV4(1);
+	SIM_CLKDIV1 = SIM_CLKDIV1_OUTDIV1(1) | SIM_CLKDIV1_OUTDIV2(1) | SIM_CLKDIV1_OUTDIV3(1) | SIM_CLKDIV1_OUTDIV4(1);
   #elif defined(KINETISL)
 	SIM_CLKDIV1 = SIM_CLKDIV1_OUTDIV1(1) | SIM_CLKDIV1_OUTDIV4(0);
   #endif
 	// here we can go into vlpr?
 	// config divisors: 4 MHz core, 4 MHz bus, 4 MHz flash
   #if defined(KINETISK)
-	SIM_CLKDIV1 = SIM_CLKDIV1_OUTDIV1(3) | SIM_CLKDIV1_OUTDIV2(3) | SIM_CLKDIV1_OUTDIV4(3);
+	SIM_CLKDIV1 = SIM_CLKDIV1_OUTDIV1(3) | SIM_CLKDIV1_OUTDIV2(3) | SIM_CLKDIV1_OUTDIV3(3) | SIM_CLKDIV1_OUTDIV4(3);
   #elif defined(KINETISL)
 	SIM_CLKDIV1 = SIM_CLKDIV1_OUTDIV1(3) | SIM_CLKDIV1_OUTDIV4(0);
   #endif