Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Freescale Semiconductor/MK21D5WS/I2C0/F#0x0
MULT=00
I2C Frequency Divider register
ClockRate
no description available
0 (00): mul = 1
1 (01): mul = 2
2 (10): mul = 4
3 (11): Reserved
https://github.com/cmsis-svd/cmsis-svd-data